config: raftv2 use enable bucket split by default (#6432)

[ti-chi-bot]

This is an automated cherry-pick of #6432

What problem does this PR solve?

Issue Number: Close #6433

What is changed and how does it work?

 MaxMovableHotPeerSize is enable in raftkv2.

Check List

Tests

• Unit test

Code changes

Side effects

Related changes

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

Release note

 MaxMovableHotPeerSize is enable in raftkv2.

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• bufferflies
• lhy1024

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[bufferflies]

/merge

[ti-chi-bot]

@bufferflies: It seems you want to merge this PR, I will help you trigger all the tests:

/run-all-tests

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[ti-chi-bot]

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

Commit hash: d5ff4f2