checker: priority to fix orphan peers

[nolouch]

What problem does this PR solve?

ref #3521
the problem is when offline a store, we may add learner multiple times if the operator is timeout.

What is changed and how it works?

Check List

Tests

• Unit test
• Manual test (add detailed scripts or steps below)

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• PR to update pingcap/tidb-ansible:
• Need to cherry-pick to the release branch

Release note

[disksing]

need any test?

[disksing]

basically LGTM except for lack of tests.

[nolouch]

PTAL @disksing @HunDunDM

[codecov]

Codecov Report

Merging #3522 (24b9b7b) into master (c4f22fd) will increase coverage by 0.04%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #3522      +/-   ##
==========================================
+ Coverage   74.56%   74.61%   +0.04%     
==========================================
  Files         245      245              
  Lines       24068    24068              
==========================================
+ Hits        17947    17958      +11     
+ Misses       4509     4504       -5     
+ Partials     1612     1606       -6     

Flag	Coverage Δ
unittests	74.61% <100.00%> (+0.04%)	⬆️

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

Impacted Files	Coverage Δ
server/schedule/checker/rule_checker.go	80.00% <100.00%> (-0.72%)	⬇️
server/schedulers/shuffle_hot_region.go	54.73% <0.00%> (-9.48%)	⬇️
server/tso/global_allocator.go	70.80% <0.00%> (-6.57%)	⬇️
server/id/id.go	76.19% <0.00%> (-4.77%)	⬇️
server/tso/local_allocator.go	80.28% <0.00%> (-2.82%)	⬇️
client/base_client.go	83.24% <0.00%> (-2.17%)	⬇️
pkg/btree/btree.go	85.30% <0.00%> (-0.97%)	⬇️
server/server.go	71.98% <0.00%> (ø)
client/client.go	72.24% <0.00%> (+0.13%)	⬆️
... and 7 more

---

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[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• HunDunDM
• lhy1024

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by writing /lgtm in a comment.
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[nolouch]

/merge

[ti-chi-bot]

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

/run-all-tests

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: 4737707

[sonarqubecloud]

SonarCloud Quality Gate failed.

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

No Coverage information
4.2% Duplication

[nolouch]

/build

[ti-srebot]

cherry pick to release-4.0 in PR #3529

[ti-srebot]

cherry pick to release-5.0 in PR #3530