etcd_worker: batch etcd patch (#3277)

[ti-chi-bot]

This is an automated cherry-pick of #3277.

This PR include #3848 #3667 #3681.

close #3848
close #3667

What problem does this PR solve?

This PR is an improvement to the issue's(#3112 ) fix.

What is changed and how it works?

1. Batch as many changefeed patches as possible into a batch and submit them as an etcd transaction, which can reduce the etcd qps.
   2. Get the response from etcd watchCh as much as possible to reduce the number of etcd worker tick reactor.
2. Add metrics for some key points in EtcdWorker.

Check List

Tests

• Unit test

Side effects

• Possible performance regression
• Increased code complexity

Related changes

• Need to cherry-pick to the release branch

Release note

Please add a release note.
If you don't think this PR needs a release note then fill it with `None`.

[ti-chi-bot]

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[asddongmen]

/run-integration-tests

[asddongmen]

/run-integration-tests

[overvenus]

/run-kafka-integration-test
/run-integration-tests

[overvenus]

/merge

[ti-chi-bot]

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

Commit hash: 394261a