store/copr: fix building cop task for global kill

[xuyifangreeneyes]

What problem does this PR solve?

Issue Number: ref #36108 ref #37421

Problem Summary:

What is changed and how it works?

After #36108 or #37421, global kill request doesn't build any cop task so global kill doesn't take effect. We adjust the logic of building cop tasks so that global kill request can build the cop task, which will be sent to another TiDB for executing kill command.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

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

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• chrysan
• winoros

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[xuyifangreeneyes]

/run-unit-test

[xuyifangreeneyes]

/run-e2e-test

[chrysan]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: b77edc8

[chrysan]

/merge