cdc: changefeed failed if the checkpoint smaller than the gc safe point

[3AceShowHand]

What problem does this PR solve?

Issue Number: close #3665, close #3939

What is changed and how it works?

make sure the changefeed level gc safe point is always removed if meet error.

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

`None`

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[gemini-code-assist]

Summary of Changes

Hello @3AceShowHand, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request refactors the changefeed creation process to enhance robustness around garbage collection (GC) safe points. It ensures that any GC safe point established during the creation of a changefeed is reliably removed if the creation process encounters an error, preventing potential resource leaks or inconsistencies. This improves the stability and error handling of changefeed management by guaranteeing proper resource deallocation even in failure scenarios.

Highlights

• GC Safe Point Cleanup: Implemented a deferred mechanism to ensure that the GC safe point is reliably removed if the changefeed creation process fails at any intermediate step.
• Improved Error Handling: Introduced a needRemoveGCSafePoint flag and a defer statement to manage the conditional cleanup of the GC safe point across various error paths during changefeed creation.
• Logging Enhancements: Refined logging messages within the GC service to provide clearer information about safe point operations and better error reporting during undo operations.

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[gemini-code-assist]

Code Review

This pull request refactors the GC safepoint handling logic during changefeed creation. The core change is moving the EnsureChangefeedStartTsSafety call and introducing a deferred cleanup function UndoEnsureChangefeedStartTsSafety to be called on failure paths. This is a good improvement for resource management. However, I've identified a potential error-masking bug in the implementation of the deferred cleanup function where it incorrectly overwrites a function-scoped error variable. My review includes a comment with a suggested fix for this issue. Additionally, some logging messages have been improved for better clarity, which is a welcome change.

[3AceShowHand]

/test all

[3AceShowHand]

/test all

[3AceShowHand]

/test all

[3AceShowHand]

/test all

[ti-chi-bot]

@3AceShowHand: 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-error-log-review	95df0b0	link	true	/test pull-error-log-review
pull-cdc-pulsar-integration-light	95df0b0	link	false	/test pull-cdc-pulsar-integration-light
pull-cdc-storage-integration-light	95df0b0	link	true	/test pull-cdc-storage-integration-light
pull-cdc-mysql-integration-light	95df0b0	link	true	/test pull-cdc-mysql-integration-light

Full PR test history. Your PR dashboard.

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