config: fix Clone in RatelimitConfig

[CabinfeverB]

What problem does this PR solve?

Issue Number: Close #7288

What is changed and how does it work?

Check List

Tests

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

Code changes

• Has the configuration change
• Has HTTP API interfaces changed (Don't forget to add the declarative for the new API)
• Has persistent data change

Side effects

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

Related changes

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

Release note

None.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• HuSharp
• rleungx

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[codecov]

Codecov Report

Merging #7289 (5cc30c8) into master (ce0bb5d) will decrease coverage by 0.13%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #7289      +/-   ##
==========================================
- Coverage   74.40%   74.28%   -0.13%     
==========================================
  Files         446      446              
  Lines       48282    48288       +6     
==========================================
- Hits        35925    35871      -54     
- Misses       9189     9232      +43     
- Partials     3168     3185      +17     

Flag	Coverage Δ
unittests	74.28% <100.00%> (-0.13%)	⬇️

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[HuSharp]

LGTM!

[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

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[ti-chi-bot]

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

Commit hash: 5cc30c8