server: fix flaky test by using t.TempDir

[hawkingrei]

What problem does this PR solve?

Issue Number: close #56735

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.

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.

None

[hawkingrei]

/check-issue-triage-complete

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 56.4381%. Comparing base (e13bfeb) to head (115a6b8).
Report is 7 commits behind head on master.

Additional details and impacted files

@@                Coverage Diff                @@
##             master     #56737         +/-   ##
=================================================
- Coverage   73.3262%   56.4381%   -16.8882%     
=================================================
  Files          1630       1756        +126     
  Lines        450312     631715     +181403     
=================================================
+ Hits         330197     356528      +26331     
- Misses        99833     251235     +151402     
- Partials      20282      23952       +3670     

Flag	Coverage Δ
integration	36.8919% <ø> (?)
unit	72.7078% <ø> (+0.2476%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	52.9478% <ø> (ø)
parser	∅ <ø> (∅)
br	53.0216% <ø> (+7.4329%)	⬆️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lance6716, winoros

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-10-21 07:48:40.539456727 +0000 UTC m=+250921.236247333: ☑️ agreed by lance6716.
• 2024-10-21 16:12:47.402440954 +0000 UTC m=+281168.099231563: ☑️ agreed by winoros.