sink: ignore the empty row event (#3144)

[ti-chi-bot]

This is an automated cherry-pick of #3144

What problem does this PR solve?

close https://github.com/pingcap/ticdc/issues/2612.

What is changed and how it works?

ignore the empty row event.

Check List

Tests

• Unit test (TBD)

Code changes

None

Side effects

None

Related changes

• Need to cherry-pick to the release branch

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has not been approved.

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[overvenus]

/merge

[ti-chi-bot]

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

Commit hash: 1b4a101

[ti-chi-bot]

@ti-chi-bot: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (release-5.1@094f14a). Click here to learn what that means.
The diff coverage is n/a.

❗ Current head 477a492 differs from pull request most recent head 36938cc. Consider uploading reports for the commit 36938cc to get more accurate results

@@               Coverage Diff                @@
##             release-5.1      #3150   +/-   ##
================================================
  Coverage               ?   57.9359%           
================================================
  Files                  ?        165           
  Lines                  ?      19437           
  Branches               ?          0           
================================================
  Hits                   ?      11261           
  Misses                 ?       7102           
  Partials               ?       1074