scheduler(ticdc): revert 3b8d55 and do not return error when resolvedTs less than checkpoint (#9953)

[ti-chi-bot]

This is an automated cherry-pick of #9953

What problem does this PR solve?

Issue Number: ref #9830, ref #9926

What is changed and how it works?

Check List

Tests

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

Questions

Will it cause performance regression or break compatibility?

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

Release note

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[CharlesCheung96]

Batch cherry-pick in #9887.

[ti-chi-bot]

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[ti-chi-bot]

@ti-chi-bot: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
pull-cdc-integration-mysql-test	f3b1df2	link	true	/test cdc-integration-mysql-test
jenkins-ticdc/verify	f3b1df2	link	true	/test verify

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