[fix](regression) Wait row count before hot value analyze

[yujun777]

What problem does this PR solve?

Issue Number: None

Related PR: None

Problem Summary:

The hot value analyze regression test can run sample analyze before Cloud table row count metadata is reported. In that state sample analyze treats the table as empty and writes empty column statistics, making the test flaky. This PR waits for SHOW DATA to report the inserted row count before running analyze on non-empty test tables.

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

Tests:

./build.sh --fe
./run-regression-test.sh --run -d statistics -s test_full_analyze_hot_value
git diff --check

[hello-stephen]

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?

[yujun777]

run buildall

[hello-stephen]

/review

[github-actions]

PR approved by at least one committer and no changes requested.

[github-actions]

PR approved by anyone and no changes requested.

[github-actions]

Review result: no blocking issues found.

Critical checkpoint conclusions:

• Goal and proof: The PR addresses a flaky hot-value analyze regression by waiting until FE metadata reports the inserted row count before running analyze. The added waits cover each non-empty table introduced before analyze, and the existing regression test is the proof target.
• Scope: The change is small and focused on the affected regression suite. It follows an existing helper pattern used by other statistics tests.
• Concurrency/lifecycle: No product concurrency or lifecycle changes. The polling loop only waits for asynchronously reported row-count metadata in test execution.
• Configuration/compatibility: No new configs, protocol, storage, or compatibility changes.
• Parallel paths: Existing statistics tests already use similar SHOW DATA/master-FE polling; this PR applies the same approach to the missing hot-value suite.
• Tests/results: The PR modifies only a regression test and reports ./run-regression-test.sh --run -d statistics -s test_full_analyze_hot_value. I did not rerun tests in this review.
• Observability/performance: Test-only logging and polling are acceptable for this regression context; no runtime observability or performance impact.
• Transactions/persistence/data writes: No product transaction or persistence path changes.
• User focus: No additional user-provided review focus was specified.