expression: improve assertion to fix flaky test

[hawkingrei]

What problem does this PR solve?

Issue Number: close #64156

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

[ti-chi-bot]

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[hawkingrei]

/retest

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 73.4838%. Comparing base (85e6857) to head (13994cc).
⚠️ Report is 3 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #64177        +/-   ##
================================================
+ Coverage   72.6867%   73.4838%   +0.7970%     
================================================
  Files          1858       1859         +1     
  Lines        502672     503466       +794     
================================================
+ Hits         365376     369966      +4590     
+ Misses       115060     111479      -3581     
+ Partials      22236      22021       -215     

Flag	Coverage Δ
integration	41.9057% <0.0000%> (?)
unit	72.6269% <100.0000%> (+0.3790%)	⬆️

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

Components	Coverage Δ
dumpling	52.8700% <ø> (ø)
parser	∅ <ø> (∅)
br	46.4105% <ø> (+0.0480%)	⬆️

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[hawkingrei]

/retest