async-io: make v2 a log batch

[BusyJay]

What is changed and how it works?

Issue Number: Ref #12842

What's Changed:

We now map states with apply index, so there is nothing to merge.
Use a log batch for better flexibility to introduce more extra writes.

Check List

Tests

• Unit test
• Integration test

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• tabokie
• tonyxuqqi

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[BusyJay]

/merge

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This pull request has been accepted and is ready to merge.

Commit hash: ff7d85d