metrics: add data flow metrics (#2763)

[ti-chi-bot]

This is an automated cherry-pick of #2763

What problem does this PR solve?

Add data flow metrics.

Also, this PR adds chechkpoint derivative and TiKV traffics

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation
• Need to update key monitor metrics in both TiCDC document and official document

Cc #1606

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: 250916f

[amyangfei]

/run-unit-tests
/run-integration-tests

[amyangfei]

/run-integration-tests

[overvenus]

/run-integration-tests

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (release-5.1@27f81ba). Click here to learn what that means.
The diff coverage is n/a.

@@               Coverage Diff                @@
##             release-5.1      #2831   +/-   ##
================================================
  Coverage               ?   57.1581%           
================================================
  Files                  ?        164           
  Lines                  ?      19663           
  Branches               ?          0           
================================================
  Hits                   ?      11239           
  Misses                 ?       7352           
  Partials               ?       1072