kvclient(ticdc): fix kvclient takes too long time to recover (#3612)

[ti-chi-bot]

This is an automated cherry-pick of #3612

close #3191
close flaky test in kvclient: #2694 #3302 #2349 #2688 #2747

What problem does this PR solve?

1. When a tikv node which has 10k region leaders fail, we found it need more than 30min to recover.
2. We think it is abnormal for the reason that pd and tikv only need about 30s to tag a node 'disconnect' and elect a new leader.

What is changed and how it works?

1. Decrease the retry num when a new stream fail to establish to make other region try ASAP.
2. Remove PartialClone when the region fail.

Reason

• Expectation
  We use a tikv node which has about 3k region leaders as our comparison object. After test in normal case and abnormal case, we got follow results:

(1) ~ 1min for 3k region to finish init scan and get event (normal case)
(2) > 20min for all 3k region to recover the stream (tikv node fail)

But, pd and tikv only need about 30s to tag a node 'disconnect' and elect a new leader, so a reasonable timespan to recover is about:

       1min30s(normal case + region failover) ~ 5min (retry control in cdc)

• Consider the probability of network jitter >> tikv temporary down >> tikv permanent down, we still need some retry logic, so

Decrease the retry num when a new stream fail to establish  to make other region try ASAP.

• When a region fail and call RegionCache.OnRegionFail, it will (1) mark the store as 'needcheck' and fetch new store state of the store asynchronous, (2) move its leader to other peer to try next time and fetch new leader back. This mechanism is suitable in our case, but we find all failed region still connect to the old store which is quite strange. So we

Remove wrong PartialClone logic when the region fail in region_worker.

Result

3min30s to recover from 3k fail (after this pr)  compared to >20min (before) 

Check List

Tests

• Manual test (add detailed scripts or steps below)

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

Release note

Please add a release note.
fix kvclient takes too long time to recover

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[overvenus]

/merge

[ti-chi-bot]

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

Commit hash: 669fb2f

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