ddl: add COMMENTS column to DDL jobs and enhance job reorg meta handling (#57392)

[ti-chi-bot]

This is an automated cherry-pick of #57392

What problem does this PR solve?

Issue Number: ref #57229 #57526

Problem Summary: See #57229

What changed and how does it work?

• Add COMMENTS column to ADMIN SHOW DDL JOBS.
• Refine DDL job reorg meta initialization. For example, let "modify column"/"reorg partition" and other reorg DDL types utilize ReorgMeta.Concurrency and ReorgMeta.BatchSize.

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.

add COMMENTS column to ADMIN SHOW DDL JOBS

[codecov]

Codecov Report

Attention: Patch coverage is 85.62500% with 23 lines in your changes missing coverage. Please review.

Please upload report for BASE (release-8.5@9862e83). Learn more about missing BASE report.

Additional details and impacted files

@@               Coverage Diff                @@
##             release-8.5     #57595   +/-   ##
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Flag	Coverage Δ
integration	36.9042% <63.1250%> (?)
unit	72.5944% <79.3750%> (?)

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

Components	Coverage Δ
dumpling	52.9478% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	52.2873% <0.0000%> (?)

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-11-21 09:53:29.346992306 +0000 UTC m=+111796.966646809: ☑️ agreed by tangenta.
• 2024-11-21 10:26:43.28710708 +0000 UTC m=+113790.906761597: ☑️ agreed by hawkingrei.

[tangenta]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hawkingrei, tangenta, YuJuncen

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

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Needs approval from an approver in each of these files:

• OWNERS [YuJuncen,hawkingrei,tangenta]
• br/OWNERS [YuJuncen]
• pkg/ddl/OWNERS [tangenta]
• pkg/meta/OWNERS [tangenta]
• pkg/planner/OWNERS [hawkingrei]

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