chore: Use force mode with risectl unregister-workers.

[shanicky]

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What's changed and what's your intention?

Add --check-fragment-occupied flag to enhance unregister_workers function

Implemented a new feature in unregister_workers and updated CLI options to improve worker unregistering process.

• Addition of a boolean parameter check_fragment_occupied to unregister_workers in reschedule.rs.
• Modification of unregister_workers to include a check for an occupied fragment if check_fragment_occupied is true.
• Integration of check_fragment_occupied as a CLI argument (--check-fragment-occupied) with a default value of false in MetaCommands::UnregisterWorkers within lib.rs.
• Update the start_impl function call to unregister_workers to pass the new CLI argument.

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have added test labels as necessary. See details.
• I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features Sqlsmith: Sql feature generation #7934).
• My PR contains breaking changes. (If it deprecates some features, please create a tracking issue to remove them in the future).
• All checks passed in ./risedev check (or alias, ./risedev c)
• My PR changes performance-critical code. (Please run macro/micro-benchmarks and show the results.)

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Documentation

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Release note

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