DDL(ticdc): add more online DDL debug log

[maxshuang]

What problem does this PR solve?

Issue Number: close #4066

What is changed and how it works?

add DDL job debug log before being skip

`None`.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• amyangfei
• overvenus

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[codecov-commenter]

Codecov Report

Merging #4237 (3d3f9d0) into master (08da001) will increase coverage by 0.0397%.
The diff coverage is 52.0379%.

Flag	Coverage Δ
cdc	58.6520% <57.6412%> (+0.0072%)	⬆️
dm	52.2619% <40.5451%> (+0.0073%)	⬆️

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

@@               Coverage Diff                @@
##             master      #4237        +/-   ##
================================================
+ Coverage   55.1722%   55.2120%   +0.0397%     
================================================
  Files           485        491         +6     
  Lines         59829      60936      +1107     
================================================
+ Hits          33009      33644       +635     
- Misses        23484      23919       +435     
- Partials       3336       3373        +37     

[ti-chi-bot]

@zhaoxinyu: Thanks for your review. The bot only counts approvals from reviewers and higher roles in list, but you're still welcome to leave your comments.

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[amyangfei]

/merge

[ti-chi-bot]

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

Commit hash: 3d3f9d0

[lance6716]

/run-verify

[maxshuang]

/run-verify