statstest: make test faster

[hawkingrei]

What problem does this PR solve?

Issue Number: ref #44940

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

[codecov]

Codecov Report

Merging #45772 (1cc6723) into master (62d0271) will increase coverage by 0.3236%.
Report is 11 commits behind head on master.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #45772        +/-   ##
================================================
+ Coverage   73.3357%   73.6594%   +0.3236%     
================================================
  Files          1271       1274         +3     
  Lines        392950     396001      +3051     
================================================
+ Hits         288173     291692      +3519     
+ Misses        86401      86036       -365     
+ Partials      18376      18273       -103     

Flag	Coverage Δ
integration	78.1388% <ø> (?)
unit	73.6517% <ø> (+0.3159%)	⬆️

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

Components	Coverage Δ
dumpling	54.0444% <ø> (ø)
parser	85.0359% <ø> (ø)
br	52.0821% <ø> (+0.0691%)	⬆️

[hawkingrei]

/test all

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [winoros,xhebox]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-08-03 06:19:52.082011537 +0000 UTC m=+339076.024360067: ☑️ agreed by winoros.
• 2023-08-03 08:47:19.792893498 +0000 UTC m=+347923.735242029: ☑️ agreed by xhebox.