in_memory_engine: fix the assert panic caused by gc

[glorv]

What is changed and how it works?

Issue Number: Close #17667

What's Changed:

Fix the bug that when region is split before gc task start, the gc task
only mark in_gc state for the region with the same id, but will unset
it for all the regions within the given range.

NOTE: for implementation simplicity, after this change, in the condition,
the gc will only run on the region with the same id, other regions in
the same range will skip this GC round.

Related changes

• PR to update pingcap/docs/pingcap/docs-cn:
• Need to cherry-pick to the release branch

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

Release note

None

[ti-chi-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: overvenus, SpadeA-Tang

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[ti-chi-bot]

[LGTM Timeline notifier]

Timeline:

• 2024-10-18 07:30:27.316469006 +0000 UTC m=+601824.465378836: ☑️ agreed by SpadeA-Tang.
• 2024-10-18 12:34:42.01256851 +0000 UTC m=+8882.709359112: ☑️ agreed by overvenus.