client: remove failed request metrics for background setting query

[CabinfeverB]

What problem does this PR solve?

Issue Number: Close #7926

What is changed and how does it work?

Check List

Tests

• Unit test

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
• nolouch

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[codecov]

Codecov Report

Merging #7925 (70a4a69) into master (5ebef84) will increase coverage by 0.05%.
The diff coverage is n/a.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7925      +/-   ##
==========================================
+ Coverage   73.47%   73.53%   +0.05%     
==========================================
  Files         436      436              
  Lines       48351    48349       -2     
==========================================
+ Hits        35528    35555      +27     
+ Misses       9755     9738      -17     
+ Partials     3068     3056      -12     

Flag	Coverage Δ
unittests	73.53% <ø> (+0.05%)	⬆️

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[HuSharp]

/merge

[ti-chi-bot]

@HuSharp: 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: 70a4a69

[ti-chi-bot]

In response to a cherrypick label: new pull request created to branch release-7.5: #7927.