external: remove old compatibility check of BR (#50534)

[ti-chi-bot]

This is an automated cherry-pick of #50534

What problem does this PR solve?

Issue Number: close #50533

Problem Summary:

What changed and how does it work?

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

[Benjamin2037]

LGTM

[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-01-18 04:59:54.91250102 +0000 UTC m=+418436.476798710: ☑️ agreed by Benjamin2037.
• 2024-01-18 07:09:39.547384045 +0000 UTC m=+426221.111681747: ☑️ agreed by lance6716.

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3pointer, Benjamin2037, lance6716

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[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-7.6@c4df22d). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-7.6     #50537   +/-   ##
================================================
  Coverage               ?   70.0149%           
================================================
  Files                  ?       1436           
  Lines                  ?     419235           
  Branches               ?          0           
================================================
  Hits                   ?     293527           
  Misses                 ?     105398           
  Partials               ?      20310           

Flag	Coverage Δ
unit	70.0149% <0.0000%> (?)

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

Components	Coverage Δ
dumpling	54.0269% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	49.6793% <0.0000%> (?)

[lance6716]

/retest

[Benjamin2037]

/retest