[sollhui]

What problem does this PR solve?

Related PR: #66350

Backport #66350 to branch-4.2 to unify BE and Recycler object-storage clients under common/cpp/obj-client, including shared provider implementations, credential factories, rate-limit decorators, listing and recursive deletion.

Resolve branch conflicts while preserving 4.2's native GCP client construction and GCS V4 signed URLs, container credential token-file support, bounded S3 response streams, and read error diagnostics. Omit changes to Kinesis and Hive code/tests absent from 4.2, and omit Recycler fault-injection configuration absent from this branch.

Release note

None

Check List (For Author)

• Test:
  • Compilation and tests skipped as requested.
  • C++ formatting checked with clang-format 16.0.5; git diff --check passes.
  • CI requested with run buildall.
• Behavior changed: Same object-client refactor as [refactor](storage) Unify BE and Recycler object clients #66350, adapted to retain existing 4.2 functionality.
• Does this need documentation: No.

[hello-stephen]

Thank you for your contribution to Apache Doris.
Don't know what should be done next? See How to process your PR.

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.
3. What features were added. Why was this function added?
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

[hello-stephen]

BE UT Coverage Report

Increment line coverage 46.19% (91/197) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	64.30% (29946/46571)
Line Coverage	49.17% (316043/642779)
Region Coverage	44.97% (254439/565814)
Branch Coverage	46.62% (120002/257389)

[hello-stephen]

BE Regression && UT Coverage Report

Increment line coverage 57.58% (114/198) 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	76.23% (34482/45233)
Line Coverage	61.12% (389648/637505)
Region Coverage	57.88% (328074/566796)
Branch Coverage	58.92% (151480/257105)

[yiguolei]

skip buildall