autoid_service: fix potential 'duplicated entry' error when tidb exit…

[YangKeao]

This is a cherry-pick of #46445

What problem does this PR solve?

Issue Number: close #46444

Problem Summary:

What is changed and how it works?

If the autoid service node is not leader, it should not save the cached id back to tikv.

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
  • See the steps in the comments of #46444
• 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

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

Fix potential 'duplicated entry' error when tidb exit for AUTO_ID_CACHE=1 tables.
The bug could happen when a tidb is the autoid_service leader previously, and exit as non-leader, it stores staled next autoid value to tikv in a force rebase way. If the value is loaded again, the autoid decreases and could cause duplicates.

[ti-chi-bot]

@YangKeao: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
idc-jenkins-ci-tidb/check_dev_2	57ef9f2	link	true	/test check-dev2

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[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: tiancaiamao

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2023-08-30 08:48:48.025186287 +0000 UTC m=+1916892.574202259: ☑️ agreed by tiancaiamao.

[YangKeao]

/retest

[YangKeao]

@tiancaiamao will submit a new PR with more logs. Close this one.