br: create database by db pool (#50771)

[ti-chi-bot]

This is an automated cherry-pick of #50771

What problem does this PR solve?

Issue Number: close #50767

Problem Summary:
br restore is very slowly if there are many databases(2000+)

What changed and how does it work?

create database by db pool

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)

40 minutes -> 5 minutes

• 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

[BornChanger]

/retest

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-7.1@25f0109). Click here to learn what that means.
The diff coverage is 56.5217%.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.1     #51027   +/-   ##
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  Coverage               ?   73.4249%           
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  Files                  ?       1210           
  Lines                  ?     378976           
  Branches               ?          0           
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  Hits                   ?     278263           
  Misses                 ?      82940           
  Partials               ?      17773           

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: BornChanger, Leavrth

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Needs approval from an approver in each of these files:

• OWNERS [Leavrth]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-02-27 08:35:42.637987196 +0000 UTC m=+951031.385610307: ☑️ agreed by BornChanger.
• 2024-02-27 09:18:11.422633234 +0000 UTC m=+953580.170256342: ☑️ agreed by Leavrth.