log backup: set a proper maxVersion to resolve lock (#57178)

[ti-chi-bot]

This is an automated cherry-pick of #57178

What problem does this PR solve?

Issue Number: close #57134

Problem Summary:

1. See issue.

What changed and how does it work?

To minimize the risk of lock conflicts, set the maxVersion to be the largest existing version value across all slow regions, incremented by 1. This adjustment helps optimize RPO by proactively reducing lock contention.

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

[ti-chi-bot]

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[ti-chi-bot]

@ti-chi-bot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/build	c5d8811	link	true	/test build
idc-jenkins-ci-tidb/check_dev	c5d8811	link	true	/test check-dev
idc-jenkins-ci-tidb/unit-test	c5d8811	link	true	/test unit-test
idc-jenkins-ci-tidb/check_dev_2	c5d8811	link	true	/test check-dev2
idc-jenkins-ci-tidb/mysql-test	c5d8811	link	true	/test mysql-test

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