statistics: gc the statistics correctly after drop the database

[0xPoe]

What problem does this PR solve?

Issue Number: close #57230

Problem Summary:

What changed and how does it work?

We overlooked handling the drop schema event in the stats DDL handler. In this PR, we'll address this by cleaning up the dropped tables one by one.

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.

修复统计信息在整个数据库被删除后无法清理的问题
Fix the issue where statistics cannot be cleaned up after the entire database is deleted.

[0xPoe]

🔢 Self-check (PR reviewed by myself and ready for feedback.)

[codecov]

Codecov Report

Attention: Patch coverage is 36.36364% with 7 lines in your changes missing coverage. Please review.

Project coverage is 74.6133%. Comparing base (a5832b4) to head (c2e60d6).
Report is 229 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #57309        +/-   ##
================================================
+ Coverage   72.9011%   74.6133%   +1.7121%     
================================================
  Files          1668       1720        +52     
  Lines        461134     476849     +15715     
================================================
+ Hits         336172     355793     +19621     
+ Misses       104308      98843      -5465     
- Partials      20654      22213      +1559     

Flag	Coverage Δ
integration	49.1011% <0.0000%> (?)
unit	72.3385% <36.3636%> (+0.0538%)	⬆️

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

Components	Coverage Δ
dumpling	52.7673% <ø> (ø)
parser	∅ <ø> (∅)
br	57.7602% <ø> (+12.6509%)	⬆️

[0xPoe]

/retest

[AilinKid]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• pkg/statistics/OWNERS [AilinKid,winoros]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-11-13 13:21:55.886849536 +0000 UTC m=+448878.077718526: ☑️ agreed by winoros.
• 2024-12-03 06:32:56.189474248 +0000 UTC m=+1136563.809128763: ☑️ agreed by AilinKid.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #58175.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.1: #58178.

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-8.5: #58179.