br: add retry for prepare flashback for backup cluster is empty and there are only one region (#41059)

[fengou1]

close #41058

What problem does this PR solve?

Issue Number: close #41058

Problem Summary:
when backup cluster is empty and there is only one region, BR assigned a leader and then do prepare a flashback immediately.
prepare flashback failed when a region was created without a leader.
region heartbeat sent may have some delay (10s), during the prepare flashback, the leader may not be sent heartbeat yet.

What is changed and how it works?

add retry for prepare flashback for specific errors.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  step as issue description br: volume-snapshot backup and restore failure when backup cluster is empty and there are only one region  #41058

- [ ] No code

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]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• 3pointer
• Leavrth

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[fengou1]

/merge

[ti-chi-bot]

@fengou1: /merge in this pull request requires 2 approval(s).

In response to this:

/merge

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[fengou1]

/hold

[fengou1]

/test build

[fengou1]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: e44733a

[fengou1]

/unhold