metrics: add old value metrics (#1618)

[ti-srebot]

cherry-pick #1618 to release-5.0
You can switch your code base to this Pull Request by using git-extras:

# In ticdc repo:
git pr https://github.com/pingcap/ticdc/pull/1652

After apply modifications, you can push your change to this PR via:

git push git@github.com:ti-srebot/ticdc.git pr/1652:release-5.0-06a3603410cb

---

What problem does this PR solve?

Cherry-pick #1571

Check List

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation

Release note

• No release note

[ti-srebot]

/run-all-tests

[zier-one]

/lgtm

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• amyangfei
• leoppro

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[zier-one]

/merge

[ti-chi-bot]

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

Commit hash: 8fcb0e5

[amyangfei]

/merge

[ti-chi-bot]

@ti-srebot: Your PR was out of date, I have automatically updated it for you.

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/run-all-tests

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