metrics: add metrics for table memory consumption (#1846)

[ti-chi-bot]

This is an automated cherry-pick of #1846

What problem does this PR solve?

• Lack of observability of processor's table memory consumption (down from the sorter)

What is changed and how it works?

• Added two Grafana panels for metrics added for flow control.

Check List

Tests

• Manual test

Related changes

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

Release note

• Add metrics for table memory consumption

[zier-one]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• amyangfei
• leoppro

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 writing /lgtm in a comment.
Reviewer can cancel approval by writing /lgtm cancel in a comment.

[amyangfei]

/merge

[ti-chi-bot]

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

Commit hash: aa94519

[liuzix]

/run-integration-test

[liuzix]

/run-kafka-integration-test

[liuzix]

/run-all-tests