Tracking issues for improving tests of ticdc

[CharlesCheung96]

Flaking unit tests

• [x] https://github.com/pingcap/tiflow/issues/10771
• [x] https://github.com/pingcap/tiflow/issues/10773
• [x] https://github.com/pingcap/tiflow/issues/10756
• [x] https://github.com/pingcap/tiflow/issues/10762
• [x] https://github.com/pingcap/tiflow/issues/10764
• [x] https://github.com/pingcap/tiflow/issues/10769
• [x] https://github.com/pingcap/tiflow/issues/10783
• [x] https://github.com/pingcap/tiflow/issues/10785
• [ ] https://github.com/pingcap/tiflow/issues/10787
• [x] https://github.com/pingcap/tiflow/issues/10815

Flaking integration tests

• [ ] #10912

Doc enhancement

• [x] https://github.com/pingcap/tiflow/pull/10746