gc: delete TiFlash placement rules in batch (#54071)

[ti-chi-bot]

This is an automated cherry-pick of #54071

What problem does this PR solve?

Issue Number: close #54068

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.

Improve performance of GC worker by deleting TiFlash placement rules in batch

[Lloyd-Pottiger]

/retest

[codecov]

Codecov Report

Attention: Patch coverage is 84.61538% with 2 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-8.1@f40e38f). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-8.1     #54406   +/-   ##
================================================
  Coverage               ?   71.1739%           
================================================
  Files                  ?       1465           
  Lines                  ?     421587           
  Branches               ?          0           
================================================
  Hits                   ?     300060           
  Misses                 ?     101048           
  Partials               ?      20479           

Flag	Coverage Δ
unit	71.1739% <84.6153%> (?)

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

Components	Coverage Δ
dumpling	53.9957% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	41.0288% <0.0000%> (?)

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: GMHDBJD, tangenta

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-07-09 06:34:33.337586596 +0000 UTC m=+339370.572820709: ☑️ agreed by GMHDBJD.
• 2024-07-10 08:13:33.922564027 +0000 UTC m=+431711.157798144: ☑️ agreed by tangenta.