metrics: change background resource group label name (#49654)

[ti-chi-bot]

This is an automated cherry-pick of #49654

What problem does this PR solve?

Issue Number: ref #49318

Problem Summary:

What changed and how does it work?

Change the resource group name from "name" to "resource_group" so we can add a global label selector later. Related tikv side change is tikv/tikv#16192.

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]

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[ti-chi-bot]

This cherry pick PR is for a release branch and has not yet been approved by triage owners.
Adding the do-not-merge/cherry-pick-not-approved label.

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[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (release-7.1@4c3389e). Click here to learn what that means.
The diff coverage is n/a.

Additional details and impacted files

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