lightning: remove alter table lock (#50074)

[ti-chi-bot]

This is an automated cherry-pick of #50074

What problem does this PR solve?

Issue Number: close #50105

Problem Summary:

What changed and how does it work?

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  import large mount of tables(each table is about several tens of MB), after this pr, we can import from 674 tables/h/instance -> 809. Since TiDB still handle alter table in serial internally, the speedup is not that obvious. Note we are importing using 10 lightning, some instance have more improvement
• 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

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-7.1@ae491e2). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

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[Benjamin2037]

LGTM

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-02-22 02:54:35.602468887 +0000 UTC m=+498564.350091989: ☑️ agreed by lance6716.
• 2024-02-22 02:56:44.378500489 +0000 UTC m=+498693.126123600: ☑️ agreed by Benjamin2037.