statistics: use slices.SortStableFunc to simple SortSampleItems

[hawkingrei]

What problem does this PR solve?

Issue Number: ref #45933

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 #47009 (1e04b20) into master (95a35f6) will decrease coverage by 0.5187%.
Report is 1 commits behind head on master.
The diff coverage is 66.6666%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #47009        +/-   ##
================================================
- Coverage   73.2353%   72.7166%   -0.5187%     
================================================
  Files          1335       1356        +21     
  Lines        397745     404027      +6282     
================================================
+ Hits         291290     293795      +2505     
- Misses        87809      91610      +3801     
+ Partials      18646      18622        -24     

Flag	Coverage Δ
integration	30.3882% <66.6666%> (?)
unit	73.0783% <66.6666%> (-0.1570%)	⬇️

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

Components	Coverage Δ
dumpling	53.9913% <ø> (ø)
parser	84.9699% <ø> (-0.0072%)	⬇️
br	48.5779% <ø> (-4.3225%)	⬇️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hi-rustin, qw4990

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-09-15 10:56:05.483332287 +0000 UTC m=+255731.450920322: ☑️ agreed by qw4990.
• 2023-09-15 11:58:20.321186225 +0000 UTC m=+259466.288774272: ☑️ agreed by hi-rustin.