sink/flowcontrol(ticdc): make tests run and refactor code

[Rustin170506]

What problem does this PR solve?

Issue Number: ref #5138

What is changed and how it works?

• make tests run and using testify
• refactor code, split file, rename fileds

Check List

Tests

• Unit test

Code changes

• Has exported function/method change
• Has exported variable/fields change

Side effects
None
Related changes
None

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• CharlesCheung96
• asddongmen

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.

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[Rustin170506]

/run-all-tests

[codecov-commenter]

Codecov Report

Merging #5264 (b837acb) into master (687e248) will increase coverage by 0.0695%.
The diff coverage is 52.0319%.

Flag	Coverage Δ
cdc	61.1131% <52.0319%> (+0.5145%)	⬆️
dm	52.3515% <ø> (-0.1180%)	⬇️

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

@@               Coverage Diff                @@
##             master      #5264        +/-   ##
================================================
+ Coverage   56.1240%   56.1935%   +0.0695%     
================================================
  Files           522        525         +3     
  Lines         65325      68426      +3101     
================================================
+ Hits          36663      38451      +1788     
- Misses        25094      26210      +1116     
- Partials       3568       3765       +197     

[CharlesCheung96]

/merge

[ti-chi-bot]

@CharlesCheung96: /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

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.

[Rustin170506]

/merge

[ti-chi-bot]

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

Commit hash: 49ed662

[ti-chi-bot]

@hi-rustin: 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.

[Rustin170506]

/run-kafka-integration-test
/run-verify

[Rustin170506]

/run-verify

[CharlesCheung96]

/run-verify