[fix](cloud) Remove flaky idempotent injection debug test

[wyxxxcat]

What problem does this PR solve?

Issue Number: close #xxx

Related PR: #56061

Problem Summary: ShortGetTabletStatsDebugStringTest enables the global idempotent request injection configuration but does not restore it after completion. Because meta_service_http_test.cpp and meta_service_test.cpp are linked into the same test binary, later tests may create delayed background bthreads.

Those tasks capture MetaServiceProxy through a raw this pointer and can access impl_ after the proxy is destroyed, causing intermittent heap-use-after-free, heap-buffer-overflow, or SEGV failures. Remove the test to prevent this test-binary-wide configuration pollution and the resulting flaky failures.

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

[hello-stephen]

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[hello-stephen]

run cloudut

[hello-stephen]

skip buildall