*: try to make TestTuner stable

[hawkingrei]

What problem does this PR solve?

Issue Number: close #41280

Problem Summary:

What is changed and how it works?

Check List

Tests

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

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

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[codecov]

Codecov Report

Merging #46215 (5cfa3b3) into master (6188778) will decrease coverage by 0.6747%.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #46215        +/-   ##
================================================
- Coverage   73.3768%   72.7021%   -0.6747%     
================================================
  Files          1285       1306        +21     
  Lines        394364     400556      +6192     
================================================
+ Hits         289372     291213      +1841     
- Misses        86557      90841      +4284     
- Partials      18435      18502        +67     

Flag	Coverage Δ
integration	25.6214% <ø> (?)
unit	73.3768% <ø> (ø)

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

Components	Coverage Δ
dumpling	54.0444% <ø> (ø)
parser	85.0765% <ø> (ø)
br	47.9218% <ø> (-4.3707%)	⬇️