[refactor](storage) Unify BE and Recycler object clients

[sollhui]

1. What does this PR do?

BE and Cloud Recycler currently maintain separate object-storage abstractions and separate S3/Azure client implementations. Although they call the same provider SDKs, they duplicate credential construction, error conversion, metrics, pagination, batch deletion, and provider-specific compatibility logic. The two implementations have also evolved different APIs and behavior, which makes fixes easy to apply to only one side.

This PR consolidates the provider-independent interface and the S3/Azure implementations under common/cpp/client:

• Add one shared ObjStorageClient interface and shared request/response types.
• Move the S3 and Azure provider clients, common stream helpers, latency metrics, and credential factories into common/cpp/client.
• Replace BE's eager list API and Recycler's separate iterator with one paginated ObjectListIterator.
• Move recursive-delete orchestration into the shared client and expose provider capabilities such as maximum delete batch size.
• Keep BE- and Recycler-specific policy outside the provider clients through runtime hooks and thin adapters.
• Extend ObjectStoreInfoPB with the optional AWS session token so AK/SK/token credentials follow the same path in BE and Recycler; redact the token from logs and debug output.
• Remove the duplicated BE clients, Recycler clients, and the BE rate-limiting decorator.

Before the refactor, BE and Recycler reached the same provider SDKs through parallel implementations, with cross-cutting behavior duplicated on both sides:

                                     BEFORE

  +---------------------- BE ----------------------+     +------------------- Recycler -------------------+
  |                                                |     |                                                |
  |  BE call sites -> S3ClientFactory              |     |  Recycler call sites -> S3Accessor            |
  |                       |                        |     |                       |                        |
  |                       v                        |     |                       v                        |
  |  RateLimitedObjStorageClient                   |     |  Recycler limiter / fault injection           |
  |                       |                        |     |                       |                        |
  |                       v                        |     |                       v                        |
  |  Separate BE S3 / Azure clients                |     |  Separate Recycler S3 / Azure clients          |
  |  credentials / eager listing / recursive delete|     |  credentials / lazy listing / recursive delete |
  |  error conversion / metrics                    |     |  error conversion / metrics                    |
  +------------------------+-----------------------+     +------------------------+-----------------------+
                           |                                                        |
                           +---------------------------+----------------------------+
                                                       |
                                                       v
                                              AWS SDK / Azure SDK

After the refactor, BE and Recycler remain separate policy owners at the top, while both depend on one shared provider layer centered below them:

                                      AFTER

  +---------------------- BE ----------------------+     +------------------- Recycler -------------------+
  |                                                |     |                                                |
  |  BE call sites                                 |     |  Recycler call sites                           |
  |       |                                        |     |       |                                        |
  |       v                                        |     |       v                                        |
  |  ObjClientHolder / S3ClientFactory             |     |  S3Accessor / ListIterator adapter             |
  |       |                                        |     |       |                                        |
  |       v                                        |     |       v                                        |
  |  BE runtime hooks                              |     |  Recycler runtime hooks                        |
  |  - QPS/bytes limiter                           |     |  - existing limiter                           |
  |  - bucket-selection policy                     |     |  - fault injection                            |
  |                                                |     |  - recursive-delete executor                  |
  +------------------------+-----------------------+     +------------------------+-----------------------+
                           |                                                        |
                           +---------------------------+----------------------------+
                                                       |
                                                       v
                      +---------------- common/cpp/client ----------------+
                      |                                                   |
                      |  ObjStorageClient + common request/response       |
                      |                         |                         |
                      |              +----------+----------+              |
                      |              |                     |              |
                      |              v                     v              |
                      |     S3ObjStorageClient    AzureObjStorageClient   |
                      |                                                   |
                      |  paginated iterator / recursive-delete engine    |
                      |  provider batch limits / error and HTTP metadata  |
                      |  latency and failure metrics                      |
                      |              |                     |              |
                      |              v                     v              |
                      |           AWS SDK              Azure SDK          |
                      +---------------------------------------------------+

The key boundary is that provider mechanics are shared, while environment-specific decisions remain in BE and Recycler adapters. This prevents the S3/Azure implementations from depending on BE or Recycler configuration and keeps future provider fixes in one place.

Validation: local compilation and tests were not run as requested. The changed C++ files were formatted, and the final patch passed static whitespace, stale-include, and conflict-marker checks.

2. How are the different behaviors unified?

Behavior	BE before	Recycler before	Unified behavior
Client API	doris::io::ObjStorageClient, using BE Status-style codes and eager list results	doris::cloud::ObjStorageClient, using integer return codes and a separate iterator API	One doris::ObjStorageClient and one set of request/response types. doris::io aliases keep BE call sites source-compatible, while Recycler adapters convert the shared response back to its existing integer-facing API.
Provider implementation	Separate BE S3/Azure clients	Separate Recycler S3/Azure clients	One S3 client and one Azure client in common/cpp/client; both BE and Recycler call the same provider code.
Error model	BE status code plus HTTP code/request ID in selected paths	Recycler-specific ret and error message	ObjectStorageResponse always carries a Doris status code, HTTP code, and request ID. Provider failures continue updating record_object_request_failed. Local BE limiter rejection keeps HTTP code 0, so it remains distinct from a provider HTTP 429.
End of listing	Eager list returned a completed vector	Iterator used false/empty to indicate completion	END_OF_FILE is an internal iterator sentinel and is converted to a successful empty result by next(). It is distinct from a real provider NOT_FOUND, so a provider 404 is not silently swallowed.
Pagination	BE fetched all S3/Azure pages inside one logical call	Recycler fetched pages lazily	Both use the same lazy iterator. Every page is one real provider request, with its own latency measurement and rate-limit admission.
Missing S3 prefix	NoSuchKey was treated as an empty list for S3-compatible providers such as TOS	Same compatibility was maintained separately	The shared S3 iterator preserves the NoSuchKey-as-empty behavior once for both callers.
Recursive deletion	BE and Recycler had different recursive-delete implementations	Recycler supported expiration filtering, a worker pool, and configurable tasks per batch	Shared orchestration performs listing, expiration filtering, task grouping, and error propagation. BE uses the synchronous defaults; Recycler injects its existing executor and recycler_max_tasks_per_batch.
Delete batch size	S3 and Azure batching was embedded in each BE client	Separate provider batching existed in Recycler	Provider capability reports the limit (1000 for S3 and 256 for Azure). Shared recursive deletion uses that limit, and direct oversized delete calls are still split defensively by the provider client.
AWS credentials	BE constructed v1/v2 providers in S3ClientFactory; empty credentials meant anonymous access	Recycler maintained another provider-construction path; empty credentials used the default chain	AwsCredentialFactory implements static AK/SK/session-token credentials, provider chains, role ARN, and external ID once. The caller explicitly selects the previous empty-credential behavior: ANONYMOUS for BE and DEFAULT_CHAIN for Recycler.
Azure credentials	BE created a shared-key credential and kept it for presigned URLs	Recycler created its own shared-key credential	AzureAuthFactory creates the container client and shared-key credential for both. BE's TLS CA diagnostic context remains attached to Azure errors.
Session token	S3ClientConf supported a token, but ObjectStoreInfoPB did not carry it through the storage-vault path	Recycler could not consume an AK/SK session token from ObjectStoreInfoPB	ObjectStoreInfoPB -> S3Conf -> AwsCredentialFactory now carries AK/SK/token consistently. Token values are cleared or masked before logging.
Rate limiting	BE admitted client operations through its limiter, with different bucket-selection policy in cloud and non-cloud modes	Recycler invoked its own limiter and fault injection around provider operations	The shared clients expose runtime hooks and acquire admission immediately before each SDK call, including every list page and provider-sized delete batch. BE and Recycler inject their existing limiter and environment-specific policy independently.
Latency metrics	BE and Recycler each used their own stopwatch macro around duplicated calls	Same metrics were recorded through separate helpers	Provider clients use a private client_bvar::ScopedLatency RAII timer. Public/common stopwatch utilities are unchanged.
Recycler-only control APIs	BE implementations and tests needed unrelated stubs when sharing an interface	S3 lifecycle, versioning, and multipart-abort APIs were Recycler-facing	These APIs are part of the shared interface with a default not-supported response. Provider clients implement the supported behavior, while unrelated BE mocks no longer need dummy methods.

[hello-stephen]

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Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
2. Which behaviors were modified. What was the previous behavior, what is it now, why was it modified, and what possible impacts might there be.
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4. Which code was refactored and why was this part of the code refactored?
5. Which functions were optimized and what is the difference before and after the optimization?

[sollhui]

run buildall

[sollhui]

/review

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[sollhui]

run buildall

[sollhui]

/review

[sollhui]

run buildall

[sollhui]

/review

[github-actions]

Codex automated review failed and did not complete.

Error: Codex completed, but no new pull request review was submitted for the current head SHA.
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Please inspect the workflow logs and rerun the review after the underlying issue is resolved.