br: send backup request in batch

[Leavrth]

What problem does this PR solve?

Issue Number: ref #52534

Problem Summary:
The BackupRequest contains the key range of index or small partition, whose kv data is only distributed in few regions.

What changed and how does it work?

send backup request in batch.

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

[tiprow]

Hi @Leavrth. Thanks for your PR.

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[codecov]

Codecov Report

Attention: Patch coverage is 75.80645% with 60 lines in your changes are missing coverage. Please review.

Project coverage is 74.3944%. Comparing base (b66a85c) to head (0bdd67e).

Additional details and impacted files

@@               Coverage Diff                @@
##             master     #52535        +/-   ##
================================================
+ Coverage   72.0405%   74.3944%   +2.3539%     
================================================
  Files          1508       1514         +6     
  Lines        434733     455363     +20630     
================================================
+ Hits         313184     338765     +25581     
+ Misses       102012      95228      -6784     
- Partials      19537      21370      +1833     

Flag	Coverage Δ
integration	29.5993% <72.9838%> (?)
unit	71.2276% <26.2096%> (-0.0219%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Components	Coverage Δ
dumpling	53.9957% <ø> (ø)
parser	∅ <ø> (∅)
br	55.8760% <75.8064%> (+17.5251%)	⬆️

[YuJuncen]

rest lgtm

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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Needs approval from an approver in each of these files:

• br/OWNERS [3pointer,YuJuncen]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-04-29 09:48:35.518174416 +0000 UTC m=+264269.275309991: ☑️ agreed by 3pointer.
• 2024-05-07 03:57:45.850342235 +0000 UTC m=+934419.607477808: ☑️ agreed by YuJuncen.

[Leavrth]

/ok-to-test

[Leavrth]

/retest

[Leavrth]

/retest