metrics: add changefeed checkepoint catch-up ETA (#3300)

[ti-chi-bot]

This is an automated cherry-pick of #3300

What problem does this PR solve?

Add changefeed checkepoint catch-up ETA

Check List

Tests

• Manual test (add detailed scripts or steps below)

Release note

Show changefeed checkepoint catch-up ETA in metrics.

[ti-chi-bot]

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[overvenus]

/merge

[ti-chi-bot]

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

Commit hash: 3f8ab92

[amyangfei]

/run-kafka-integration-test

[amyangfei]

/merge

[amyangfei]

/run-integration-test

[codecov-commenter]

Codecov Report

❗ No coverage uploaded for pull request base (release-5.0@c35f424). Click here to learn what that means.
The diff coverage is n/a.

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