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

[Leavrth]

/test pull-br-integration-test

[tiprow]

@Leavrth: No presubmit jobs available for pingcap/tidb@release-7.5

In response to this:

/test pull-br-integration-test

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-7.5@c061545). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.5     #51028   +/-   ##
================================================
  Coverage               ?   71.9782%           
================================================
  Files                  ?       1403           
  Lines                  ?     407616           
  Branches               ?          0           
================================================
  Hits                   ?     293395           
  Misses                 ?      94519           
  Partials               ?      19702           

Flag	Coverage Δ
unit	71.9782% <0.0000%> (?)

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

Components	Coverage Δ
dumpling	53.9913% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	53.1536% <0.0000%> (?)

[Leavrth]

/test pull-br-integration-test

[tiprow]

@Leavrth: No presubmit jobs available for pingcap/tidb@release-7.5

In response to this:

/test pull-br-integration-test

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[Leavrth]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• br/OWNERS [3pointer,Leavrth]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-02-09 03:41:39.933655622 +0000 UTC m=+501025.500425497: ☑️ agreed by Leavrth.
• 2024-02-09 07:43:19.473131453 +0000 UTC m=+515525.039901340: ☑️ agreed by 3pointer.