log backup: fix the issue that paused service safepoint not removed (#52106)

[ti-chi-bot]

This is an automated cherry-pick of #52106

What problem does this PR solve?

Issue Number: close #52082

Problem Summary:
stop task didn't remove service safepoint correctly.

What changed and how does it work?

1. set ttl == 0 to make pd service remove this safepoint.

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 the issue that stop log backup didn't clean paused task gc safepoint correctly.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [3pointer]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-03-29 11:18:34.819205544 +0000 UTC m=+10776.346746090: ☑️ agreed by 3pointer.
• 2024-03-29 11:23:53.808365985 +0000 UTC m=+11095.335906532: ☑️ agreed by BornChanger.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-6.5@30a9b5d). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

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