br: enable follower handler again

[okJiang]

What problem does this PR solve?

Issue Number: close #60085

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.

When the traffic is reduced, the state of sync can always be synchronized.

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.

Enable pd_enable_follower_handle_region during BR restore

[ti-chi-bot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[tiprow]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[codecov]

Codecov Report

Attention: Patch coverage is 59.09091% with 9 lines in your changes missing coverage. Please review.

Project coverage is 75.4856%. Comparing base (8a1ee5d) to head (a52f6fc).
Report is 20 commits behind head on master.

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #60301        +/-   ##
================================================
+ Coverage   73.1532%   75.4856%   +2.3323%     
================================================
  Files          1725       1748        +23     
  Lines        477917     491541     +13624     
================================================
+ Hits         349612     371043     +21431     
+ Misses       106876      97761      -9115     
- Partials      21429      22737      +1308     

Flag	Coverage Δ
integration	49.4387% <45.4545%> (?)
unit	72.9819% <45.4545%> (+0.6355%)	⬆️

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

Components	Coverage Δ
dumpling	52.7804% <ø> (ø)
parser	∅ <ø> (∅)
br	62.4580% <59.0909%> (+14.8856%)	⬆️

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[okJiang]

/retest

[okJiang]

/cc @3pointer

[okJiang]

/cc @3pointer @YuJuncen

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3pointer, GMHDBJD

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:

• br/OWNERS [3pointer]
• pkg/lightning/OWNERS [GMHDBJD]

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:

• 2025-05-22 05:42:02.027354461 +0000 UTC m=+71026.444414036: ☑️ agreed by 3pointer.
• 2025-05-22 06:47:40.079450233 +0000 UTC m=+74964.496509847: ☑️ agreed by GMHDBJD.

[okJiang]

/check-issue-triage-complete

[okJiang]

/retest

[okJiang]

/retest

[okJiang]

/retest