disk_snapshot_backup: pause raft log GC while backing up (#16519)

[ti-chi-bot]

This is an automated cherry-pick of #16519

What is changed and how it works?

Issue Number: Close #16518

What's Changed:

This PR will pause the `CompactLog` admin command during backing up.

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  The code change is small but the impact would be relatively huge.
  We have tested this before which shows there wouldn't be snapshot sent during restoring.
  We have disabled GC manually for minutes and see there isn't huge impact to TP workloads (But I guess not for every scenario.).
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Release note

Speeded up the restoration for newly generated backups.

[ti-chi-bot]

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[YuJuncen]

In favor of #16354

[ti-chi-bot]

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

To merge this cherry pick:

1. It must be approved by the approvers firstly.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

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