pkg/core, cluster: save kv and cache if region flashback (#6911)

[ti-chi-bot]

This is an automated cherry-pick of #6911

What problem does this PR solve?

Issue Number: ref #6912

Close tikv/tikv#15258

What is changed and how does it work?

TiKV Region merge checks region in operator and in local strictly,
and drops commit merge if there is a mismatch between them.

This change is necessary to prevent flashback from blocking
Region merge. For more details, see tikv/tikv#15258.

Check List

Tests

• Unit test

Related changes

• Need to cherry-pick to the release branch

Release note

Fix an issue that Region merge may be blocked after flashback

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• bufferflies
• nolouch

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[codecov]

Codecov Report

Patch coverage: 85.71% and project coverage change: -0.07% ⚠️

Comparison is base (4441cd8) 75.64% compared to head (1011ad7) 75.58%.

Additional details and impacted files

@@               Coverage Diff               @@
##           release-6.5    #6948      +/-   ##
===============================================
- Coverage        75.64%   75.58%   -0.07%     
===============================================
  Files              329      329              
  Lines            33595    33602       +7     
===============================================
- Hits             25414    25399      -15     
- Misses            6010     6029      +19     
- Partials          2171     2174       +3     

Flag	Coverage Δ
unittests	75.58% <85.71%> (-0.07%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
server/cluster/cluster.go	81.58% <ø> (-0.34%)	⬇️
server/core/region.go	90.12% <80.00%> (-0.08%)	⬇️
server/core/region_option.go	67.37% <100.00%> (+0.46%)	⬆️

... and 20 files with indirect coverage changes

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[overvenus]

/merge

[ti-chi-bot]

@overvenus: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

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[ti-chi-bot]

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

Commit hash: 9a9b565

[overvenus]

CI fails as follow

make[2]: Entering directory '/home/runner/work/pd/pd'
make[2]: Leaving directory '/home/runner/work/pd/pd'
level=error msg="Running error: context loading failed: no go files to analyze"
make[1]: *** [Makefile:21: static] Error 5
/usr/bin/bash: line 1: cd: ./client: No such file or directory
make[1]: Leaving directory '/home/runner/work/pd/pd/tests/client'
make: *** [Makefile:1[54](https://github.com/tikv/pd/actions/runs/5864608952/job/15899969046?pr=6948#step:5:55): static] Error 1

[ti-chi-bot]

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

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[overvenus]

/merge

[ti-chi-bot]

@overvenus: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

You only need to trigger /merge once, and if the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

If you have any questions about the PR merge process, please refer to pr process.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

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

Commit hash: 1011ad7