fix Region Exception occurred EpochNotMatch

[marsishandsome]

Signed-off-by: marsishandsome marsishandsome@gmail.com

What problem does this PR solve?

close #304

When region splits, the region info on PD may not be updated in a few seconds.
Clients should use the new region info in RegionEpochNotMatch ERROR to update the local region cache.

What is changed and how it works?

OnRegionEpochNotMatch removes the old region and inserts new regions into the cache.

ref: https://github.com/tikv/client-go/blob/tidb-5.2/internal/locate/region_request.go#L985

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has interface methods change
• Has persistent data change

Side effects

• Possible performance regression
• Increased code complexity
• Breaking backward compatibility

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation
• Need to be included in the release note

[marsishandsome]

/run-all-tests

[birdstorm]

LGTM