Add test for resume with overwrite checkpointTs

[hongyunyan]

What problem does this PR solve?

Issue Number: ref #12055

What is changed and how it works?

Add test for resume with overwrite checkpointTs

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

Please refer to [Release Notes Language Style Guide](https://pingcap.github.io/tidb-dev-guide/contribute-to-tidb/release-notes-style-guide.html) to write a quality release note.

If you don't think this PR needs a release note then fill it with `None`.

[hongyunyan]

/test pull-verify

[ti-chi-bot]

@hongyunyan: The following test 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	eb1b90a	link	true	/test pull-cdc-integration-mysql-test

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: lidezhu

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-02-12 03:03:37.526950625 +0000 UTC m=+412059.923172684: ☑️ agreed by lidezhu.