util: Resolve RuntimeStatsColl potential unlock mutex (#55118)

[ti-chi-bot]

This is an automated cherry-pick of #55118

What problem does this PR solve?

Issue Number: close #55042

Problem Summary:

What changed and how does it work?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.
    Just a mutex lock changes, using defer to protect it.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

Fix the issue that queries may get stuck when they are being killed due to exceeding tidb_mem_quota_query.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (release-7.1@4ac668d). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.1     #55647   +/-   ##
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  Hits                   ?     279441           
  Misses                 ?      83130           
  Partials               ?      17844           

[windtalker]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: guo-shaoge, windtalker

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-08-26 06:02:27.226333705 +0000 UTC m=+763742.360783809: ☑️ agreed by windtalker.
• 2024-08-26 06:28:34.763164007 +0000 UTC m=+765309.897614129: ☑️ agreed by guo-shaoge.