syncer(dm): fix failed row skipped due to incorrect checkpoint flush

[D3Hunter]

What problem does this PR solve?

Issue Number: close #5279

What is changed and how it works?

• checkpoint flush should wait all dml before it finished.

Check List

Tests

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

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation
• Need to update key monitor metrics in both TiCDC document and official document

Release note

`None`.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• GMHDBJD
• lance6716

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[D3Hunter]

/cc @lance6716 @GMHDBJD

[GMHDBJD]

LGTM

[lance6716]

/run-dm-integration-test

[lance6716]

maybe my old thought is don't let handleJob calls handleJob itself, but I forget to flush the jobs in queue 😂

I'm afraid handleJob calling handleJob itself will cause stack overflow in some bad cases, but flushIfOutdated is a common logic so it can also be put inside handleJob. No idea 🤔

[D3Hunter]

/run-dm-compatibility-test
/run-integration-test
/run-kafka-integration-test

[D3Hunter]

/merge

[ti-chi-bot]

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

Commit hash: 67c744c

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5297.