placement: return rules after clone (#3892)

[ti-chi-bot]

This is an automated cherry-pick of #3892

Signed-off-by: disksing i@disksing.com

What problem does this PR solve?

Fix #3886

What is changed and how it works?

Clone the rule before returning to callers. It should be safe to modify and update again.

Check List

Tests

• Unit test
• Integration test

Related changes

• Need to cherry-pick to the release branch

Release note

Fix an issue where data is not stored when using max-replicas or location-labels to indirectly update default placement rule

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• HunDunDM
• nolouch

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[codecov]

Codecov Report

Merging #3915 (7e41a72) into release-5.1 (31aea9b) will decrease coverage by 0.03%.
The diff coverage is 85.71%.

@@               Coverage Diff               @@
##           release-5.1    #3915      +/-   ##
===============================================
- Coverage        75.14%   75.11%   -0.04%     
===============================================
  Files              245      245              
  Lines            24600    24614      +14     
===============================================
+ Hits             18486    18488       +2     
- Misses            4500     4510      +10     
- Partials          1614     1616       +2     

Flag	Coverage Δ
unittests	75.11% <85.71%> (-0.04%)	⬇️

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

Impacted Files	Coverage Δ
server/server.go	72.03% <50.00%> (+0.71%)	⬆️
pkg/typeutil/comparison.go	85.71% <60.00%> (-14.29%)	⬇️
server/schedule/placement/rule.go	96.15% <100.00%> (+0.40%)	⬆️
server/schedule/placement/rule_manager.go	83.13% <100.00%> (+0.25%)	⬆️
pkg/tempurl/tempurl.go	45.00% <0.00%> (-15.00%)	⬇️
server/tso/global_allocator.go	70.55% <0.00%> (-5.00%)	⬇️
pkg/etcdutil/etcdutil.go	84.70% <0.00%> (-3.53%)	⬇️
server/tso/allocator_manager.go	77.46% <0.00%> (-3.51%)	⬇️
server/schedule/operator/step.go	67.44% <0.00%> (-1.67%)	⬇️
pkg/btree/btree.go	85.30% <0.00%> (-0.97%)	⬇️
... and 11 more

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[HunDunDM]

/run-unit-test

[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: 7e41a72