Fix changefeed stuck problem when overwrite resume with a forward checkpointTs

[hongyunyan]

What problem does this PR solve?

Issue Number: ref https://github.com/pingcap/tiflow/issues/12055

What is changed and how it works?

release resolvedTs when changefeed is pause

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`.

[ti-chi-bot[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: 3AceShowHand, lidezhu

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• ~~OWNERS~~ [3AceShowHand,lidezhu]

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[ti-chi-bot[bot]]

[LGTM Timeline notifier]

Timeline:

• 2025-06-30 06:33:02.456153345 +0000 UTC m=+1290235.179332331: :ballot_box_with_check: agreed by lidezhu.
• 2025-06-30 06:36:31.225172621 +0000 UTC m=+1290443.948351604: :ballot_box_with_check: agreed by 3AceShowHand.

[kennytm]

/retest

[kennytm]

/retest