br: use merge-schedule-limit to pause merge (#47576)

[ti-chi-bot]

This is an automated cherry-pick of #47576

What problem does this PR solve?

Issue Number: ref tikv/pd#7148

Problem Summary:
max-merge-region-keys is not a stable arguments.
merge-schedule-limit is more stable to control the merge operator.

What is changed and how it works?

use merge-schedule-limit instead of other arguments to control the merge operator during restore.

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

[3pointer]

/test unit-test

[tiprow]

@3pointer: No presubmit jobs available for pingcap/[email protected]

In response to this:

/test unit-test

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Please upload report for BASE (release-7.1@9a8182f). Learn more about missing BASE report.

Additional details and impacted files

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##             release-7.1     #48248   +/-   ##
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  Partials               ?      17838           

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [3pointer,Leavrth]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-11-06 07:59:57.318755313 +0000 UTC m=+1027910.157910873: ☑️ agreed by 3pointer.
• 2024-11-06 08:01:00.494611321 +0000 UTC m=+1027973.333766852: ☑️ agreed by Leavrth.