(redo)ticdc: fix the event orderliness in redo log (#11117)

[ti-chi-bot]

This is an automated cherry-pick of #11117

What problem does this PR solve?

Issue Number: close #11096

What is changed and how it works?

1. Fix the less function of logHeap to make dml event of redo log in the same txn sorted as delete/update/insert.
2. use startTs instead of commitTs in redo apply to distinguish different txns.

Check List

Tests

• Unit test

• Manual test (add detailed scripts or steps below)

  create mysql sink changefeed with redo log on
  run gotpc workload
  After 30m, pause changefeed and run redo apply

Questions

Will it cause performance regression or break compatibility?

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

Release note

None

[hongyunyan]

/retest

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CharlesCheung96

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[hongyunyan]

/retest