br: fix insert gc failed due to slow schema reload (#57742)

[ti-chi-bot]

This is an automated cherry-pick of #57742

What problem does this PR solve?

Issue Number: close #57743

Problem Summary:

What changed and how does it work?

Wait until schema info finished reloading before proceeding to the rest of the restore process,
Added test to first to reproduce the issue and then add the fix to verify the issue has been fixed (TDD)

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.

Fixed loading schema taking long time during restore causing insertGc row and other operations to fail  

[ti-chi-bot]

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[ti-chi-bot]

@ti-chi-bot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/build	8da6125	link	true	/test build
idc-jenkins-ci-tidb/unit-test	8da6125	link	true	/test unit-test
idc-jenkins-ci-tidb/mysql-test	8da6125	link	true	/test mysql-test
idc-jenkins-ci-tidb/check_dev_2	8da6125	link	true	/test check-dev2
idc-jenkins-ci-tidb/check_dev	8da6125	link	true	/test check-dev

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