executor: Fix coroutine leak after kill remote connection (#46035)

[ti-chi-bot]

This is an automated cherry-pick of #46035

What problem does this PR solve?

Issue Number: close #46034

Problem Summary: Coroutine leak after kill remote connection.

What is changed and how it works?

Close resp of coprocessor request. Otherwise the coprocessor will be blocked on the respChan.

Check List

Tests

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

Run the same test in issue, the coroutine count was stable, and no OOM occurred.

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

[pingyu]

/test mysql-test

[tiprow]

@pingyu: No presubmit jobs available for pingcap/tidb@release-6.5

In response to this:

/test mysql-test

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[pingyu]

/test mysql-test

[tiprow]

@pingyu: No presubmit jobs available for pingcap/tidb@release-6.5

In response to this:

/test mysql-test

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-6.5@a0f1d7e). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

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##             release-6.5     #46065   +/-   ##
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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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

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• OWNERS [hawkingrei,tangenta]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-08-17 07:33:30.122380962 +0000 UTC m=+789174.671396945: ☑️ agreed by tangenta.
• 2023-08-17 07:52:59.532806536 +0000 UTC m=+790344.081822520: ☑️ agreed by hawkingrei.