fix data race of LocalAdmissionController (#10332)

[ti-chi-bot]

This is an automated cherry-pick of #10332

What problem does this PR solve?

Issue Number: close #10331

Problem Summary:

What is changed and how it works?

1. fix data race of keyspace_resource_groups
2. refine the logic of handling current_tick/cur_tick_end.
3. add endRequest when got error in the logic of handling GAC resp. Otherwise this rg will enter degrade mode, and it will not acquire any tokens from GAC for DEGRADE_MODE_DURATION seconds (120s)

Check List

Tests

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

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

fix data race of LocalAdmissionController

[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.

To merge this cherry pick:

1. It must be approved by the approvers firstly.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

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[ti-chi-bot]

@guo-shaoge This PR has conflicts, I have hold it.
Please resolve them or ask others to resolve them, then comment /unhold to remove the hold label.

[ti-chi-bot]

@ti-chi-bot: ## If you want to know how to resolve it, please read the guide in TiDB Dev Guide.

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: solotzg, wshwsh12

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Needs approval from an approver in each of these files:

• OWNERS [solotzg,wshwsh12]

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2025-08-13 06:26:30.648784633 +0000 UTC m=+421589.683367871: ☑️ agreed by wshwsh12.
• 2025-08-13 06:27:00.273711561 +0000 UTC m=+421619.308294788: ☑️ agreed by solotzg.

[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.

To merge this cherry pick:

1. It must be approved by the approvers firstly.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

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 kubernetes-sigs/prow repository.

[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.

To merge this cherry pick:

1. It must be approved by the approvers firstly.
2. AFTER it has been approved by approvers, please wait for the cherry-pick merging approval from triage owners.

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 kubernetes-sigs/prow repository.

[guo-shaoge]

this pr has been tagged as next version in tirelease, and should be merged in next version.