br: fix Log Backup unexpected paused when adding a already long-running task (#53695)

[ti-chi-bot]

This is an automated cherry-pick of #53695

What problem does this PR solve?

Issue Number: close #53561

Problem Summary:

What changed and how does it work?

Now, advancer will sync checkpoint with pd when adding a new task

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.

Fix Log Backup unexpected paused when adding a long-run task

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (release-6.5@60b127f). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-6.5     #53947   +/-   ##
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  Coverage               ?   73.6299%           
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  Files                  ?       1096           
  Lines                  ?     352131           
  Branches               ?          0           
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  Hits                   ?     259274           
  Misses                 ?      76188           
  Partials               ?      16669           

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-06-12 02:17:42.830236516 +0000 UTC m=+517416.883548440: ☑️ agreed by 3pointer.
• 2024-06-12 02:26:23.78368946 +0000 UTC m=+517937.837001385: ☑️ agreed by BornChanger.