planner: introduce an interface for StatsHandle to simplify the code

[qw4990]

What problem does this PR solve?

Issue Number: ref #46905

Problem Summary: planner: introduce an interface for StatsHandle to simplify the code

What is changed and how it works?

planner: introduce an interface for StatsHandle to simplify the code

No logical change, just refactor.

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

[tiprow]

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[codecov]

Codecov Report

Merging #47670 (a12d32b) into master (54bc3a5) will increase coverage by 0.9364%.
Report is 2 commits behind head on master.
The diff coverage is 94.4444%.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #47670        +/-   ##
================================================
+ Coverage   71.9090%   72.8455%   +0.9364%     
================================================
  Files          1396       1419        +23     
  Lines        405035     411671      +6636     
================================================
+ Hits         291257     299884      +8627     
+ Misses        94168      92968      -1200     
+ Partials      19610      18819       -791     

Flag	Coverage Δ
integration	41.3567% <37.5000%> (?)
unit	71.9501% <94.4444%> (+0.0410%)	⬆️

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

Components	Coverage Δ
dumpling	53.9913% <ø> (ø)
parser	∅ <ø> (∅)
br	48.7067% <ø> (-4.2371%)	⬇️

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: AilinKid, hawkingrei

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-10-16 10:21:44.036221878 +0000 UTC m=+1652501.623332024: ☑️ agreed by AilinKid.
• 2023-10-16 10:26:25.563832278 +0000 UTC m=+1652783.150942423: ☑️ agreed by hawkingrei.