Don't check labels when user enable placement-rule

[lucklove]

From https://docs.pingcap.com/tidb/stable/configure-placement-rules:

After enabling Placement Rules, the previously configured max-replicas and location-labels no longer take effect. To adjust the replica policy, use the interface related to Placement Rules.

Fix #1371

What problem does this PR solve?

What is changed and how it works?

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

Release notes:

NONE

[codecov-commenter]

Codecov Report

Merging #1378 (614907a) into master (4171af1) will increase coverage by 24.72%.
The diff coverage is 27.27%.

@@             Coverage Diff             @@
##           master    #1378       +/-   ##
===========================================
+ Coverage   25.33%   50.06%   +24.72%     
===========================================
  Files         265      290       +25     
  Lines       20515    22400     +1885     
===========================================
+ Hits         5198    11214     +6016     
+ Misses      14517     9392     -5125     
- Partials      800     1794      +994     

Flag	Coverage Δ
cluster	35.66% <27.27%> (?)
dm	24.57% <0.00%> (?)
integrate	44.45% <27.27%> (+28.88%)	⬆️
playground	13.80% <0.00%> (?)
tiup	15.57% <0.00%> (ø)
unittest	21.64% <0.00%> (-0.01%)	⬇️

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

Impacted Files	Coverage Δ
pkg/cluster/manager/display.go	65.26% <0.00%> (+65.26%)	⬆️
pkg/cluster/api/pdapi.go	56.61% <33.33%> (+56.61%)	⬆️
pkg/cluster/manager/scale_out.go	44.44% <50.00%> (+35.45%)	⬆️
pkg/cluster/operation/scale_in.go	58.27% <0.00%> (ø)
components/playground/instance/pd.go	73.91% <0.00%> (ø)
pkg/logger/logger.go	100.00% <0.00%> (ø)
pkg/logger/audit.go	53.33% <0.00%> (ø)
pkg/cluster/operation/upgrade.go	57.27% <0.00%> (ø)
pkg/cluster/operation/destroy.go	52.88% <0.00%> (ø)
components/playground/instance/tikv.go	67.34% <0.00%> (ø)
... and 191 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 4171af1...614907a. Read the comment docs.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• AstroProfundis

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.
Reviewer can cancel approval by writing /lgtm cancel in a comment.

[AstroProfundis]

/merge

[ti-chi-bot]

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

Commit hash: aa93117

[ti-chi-bot]

@lucklove: Your PR was out of date, I have automatically updated it for you.

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.