kv-client(cdc): handle ServerIsBusy errors

[hicqu]

What problem does this PR solve?

Issue Number: close #10306

What is changed and how it works?

Handle ServerIsBusy errors in kv-client module.

Check List

Tests

• Manual test (add detailed scripts or steps below)

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

None

[hicqu]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CharlesCheung96, sdojjy

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• OWNERS [CharlesCheung96,sdojjy]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-12-14 07:05:42.78270076 +0000 UTC m=+512633.819927672: ☑️ agreed by sdojjy.
• 2023-12-14 07:22:19.699052389 +0000 UTC m=+513630.736279311: ☑️ agreed by CharlesCheung96.

[CharlesCheung96]

What does ServerIsBusy mean on the tikv side?

[hicqu]

/retest

[hicqu]

/retest

[hicqu]

/retest

[hicqu]

/retest

[ti-chi-bot]

/cherry-pick release-7.5

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #10577.

[ti-chi-bot]

@ti-chi-bot: new pull request could not be created: failed to create pull request against pingcap/tiflow#release-7.5 from head ti-chi-bot:cherry-pick-10252-to-release-7.5: status code 422 not one of [201], body: {"message":"Validation Failed","errors":[{"resource":"PullRequest","code":"custom","message":"A pull request already exists for ti-chi-bot:cherry-pick-10252-to-release-7.5."}],"documentation_url":"https://docs.github.com/rest/pulls/pulls#create-a-pull-request"}

In response to this:

/cherry-pick release-7.5

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