v8.5.5: adjust the document for admin alter ddl jobs (#22195)

[ti-chi-bot]

This is an automated cherry-pick of #22195

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• This PR is translated from: *: adjust the document for admin alter ddl jobs docs-cn#21197
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[gemini-code-assist]

Summary of Changes

Hello @ti-chi-bot, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request updates the documentation related to the ADMIN ALTER DDL JOBS command. It specifically removes information about a previous limitation where certain parameters, such as BATCH_SIZE and THREAD, were only effective when the tidb_enable_dist_task system variable was disabled. This change clarifies the current behavior and broader usability of these DDL job alteration parameters.

Highlights

• Documentation Update for ADMIN ALTER DDL JOBS: The documentation for the ADMIN ALTER DDL JOBS command has been updated to remove outdated restrictions.
• Removal of tidb_enable_dist_task Restriction: Previous notes stating that BATCH_SIZE, MAX_WRITE_SPEED, and THREAD parameters only work when tidb_enable_dist_task is disabled have been removed from the documentation, indicating broader applicability of these parameters.

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[gemini-code-assist]

Code Review

This pull request adjusts the documentation for ADMIN ALTER DDL JOBS by removing a restriction related to tidb_enable_dist_task. The changes are consistent across the modified files. My feedback focuses on improving the completeness of the documentation by suggesting to add back links to the ADMIN ALTER DDL JOBS command page, which were removed as part of the changes. This will help users navigate the documentation more easily.

[ti-chi-bot]

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