[Test](client) Add s3 storage client test for accessor

[wyxxxcat]

What problem does this PR solve?

#57456

If you want to run unit tests using a real cloud provider, you can configure it in custom_env.sh.

# Enable S3 client for unit tests
export ENABLE_S3_CLIENT=1
# S3 client config
export S3_AK="xxx"
export S3_SK="xxx"
export S3_ENDPOINT="xxx"
export S3_PROVIDER="xxx"
export S3_BUCKET="xxx"
export S3_REGION="xxx"
export S3_PREFIX=""

Release note

None

Check List (For Author)

• Test

  • Regression test
  • Unit Test
  • Manual test (add detailed scripts or steps below)
  • No need to test or manual test. Explain why:
    • This is a refactor/code format and no logic has been changed.
    • Previous test can cover this change.
    • No code files have been changed.
    • Other reason

• Behavior changed:

  • No.
  • Yes.

• Does this need documentation?

  • No.
  • Yes.

Check List (For Reviewer who merge this PR)

• Confirm the release note
• Confirm test cases
• Confirm document
• Add branch pick label

[Thearas]

Thank you for your contribution to Apache Doris.
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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.
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?

[wyxxxcat]

run cloud_ut

[hello-stephen]

Cloud UT Coverage Report

Increment line coverage 🎉

Increment coverage report
Complete coverage report

Category	Coverage
Function Coverage	80.86% (1707/2111)
Line Coverage	66.87% (29897/44708)
Region Coverage	67.43% (14912/22114)
Branch Coverage	57.59% (7929/13768)