sinkv2(ticdc): fix update resolved ts not taking effect issue

[Rustin170506]

What problem does this PR solve?

Issue Number: ref #5928

What is changed and how it works?

• delete buffer after flush
• set correct eventID
• add more tests

Check List

Tests

• Unit test

Questions

Will it cause performance regression or break compatibility?

No

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

No

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• asddongmen
• hicqu

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[Rustin170506]

/run-verify

[hicqu]

/merge

[ti-chi-bot]

@hicqu: /merge is only allowed for the committers, you can assign this pull request to the committer in list by filling /assign @committer in the comment to help merge this pull request.

In response to this:

/merge

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[Rustin170506]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: a94d4c3

[Rustin170506]

/run-verify

[codecov-commenter]

Codecov Report

Merging #6118 (f4c8145) into master (792faf7) will decrease coverage by 0.7427%.
The diff coverage is 68.8918%.

Flag	Coverage Δ
cdc	63.5760% <77.1739%> (-1.6309%)	⬇️
dm	51.8553% <43.1034%> (-0.0685%)	⬇️
engine	62.7302% <75.8454%> (+0.0990%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

@@               Coverage Diff                @@
##             master      #6118        +/-   ##
================================================
- Coverage   58.6479%   57.9052%   -0.7428%     
================================================
  Files           711        701        -10     
  Lines         83933      83141       -792     
================================================
- Hits          49225      48143      -1082     
- Misses        30258      30646       +388     
+ Partials       4450       4352        -98