[close #776] Fix prewrite & commit log info to debug(#776)

[jackjeyis]

What problem does this PR solve?

Issue Number: close #issue_number

Problem Description: TBD

What is changed and how does it work?

Code changes

• Has exported function/method change
• Has exported variable/fields change
• Has methods of interface change
• Has persistent data change
• No code

Check List for Tests

This PR has been tested by at least one of the following methods:

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

Side effects

• Possible performance regression, WHY: TBD
• Increased code complexity, WHY: TBD
• Breaking backward compatibility, WHY: TBD
• NO side effects

Related changes

• Need to cherry-pick to the release branch
• Need to update the documentation
• Need to be included in the release note
• NO related changes

[zhangyangyu]

@jackjeyis thanks for your contribution. Is there any reason to change the log info? Does it cause any problem now?