infoschema,metrics: use tidb_tikvclient_request_seconds_bucket to get the .999 cop req duration instead (#59845)

[ti-chi-bot]

This is an automated cherry-pick of #59845

What problem does this PR solve?

Issue Number: Ref #59815

Problem Summary:
The TiDB -> Distsql -> Coprocessor Seconds 999 panel uses the tidb_tikvclient_cop_duration_seconds_bucket metric to gather data, but this metric is redundant. We can use tidb_tikvclient_request_seconds_bucket to obtain the same data. Therefore, tidb_tikvclient_cop_duration_seconds_bucket can be removed to save storage space.

client-go PR tikv/client-go#1602

What changed and how does it work?

Before:

After:

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No need to test

  • I checked and no code files have been changed.

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Please refer to Release Notes Language Style Guide to write a quality release note.

None

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: MyonKeminta, zimulala

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• OWNERS [MyonKeminta,zimulala]
• pkg/infoschema/OWNERS [zimulala]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-07-21 03:22:35.512312881 +0000 UTC m=+208192.433456867: ☑️ agreed by MyonKeminta.
• 2025-07-21 03:22:52.24352367 +0000 UTC m=+208209.164667647: ☑️ agreed by zimulala.

[XuHuaiyu]

/retest

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

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Additional details and impacted files

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##             release-7.5     #60390   +/-   ##
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Flag	Coverage Δ
unit	72.1880% <ø> (?)

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Components	Coverage Δ
dumpling	52.9400% <0.0000%> (?)
parser	∅ <0.0000%> (?)
br	53.6205% <0.0000%> (?)

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