kv(ticdc): set debug level for resolved ts fallback log

[overvenus]

What problem does this PR solve?

Issue Number: ref #4146

What is changed and how it works?

Set debug level for resolved ts fallback log in kv client.
This log is not helpful in the most of time. Any region transfer may trigger the log.

Check List

Tests

• Manual test (add detailed scripts or steps below)
  See Too many repeated logs when TiDB OOM #4146

Questions

Will it cause performance regression or break compatibility?

Do you need to update user documentation, design documentation or monitoring documentation?

Release note

None

[ti-chi-bot]

[REVIEW NOTIFICATION]

This pull request has been approved by:

• 3AceShowHand

To complete the pull request process, please ask the reviewers in the list to review by filling /cc @reviewer in the comment.
After your PR has acquired the required number of LGTMs, you can assign this pull request to the committer in the list by filling /assign @committer in the comment to help you merge this pull request.

The full list of commands accepted by this bot can be found here.

Reviewer can indicate their review by submitting an approval review.
Reviewer can cancel approval by submitting a request changes review.

[3AceShowHand]

/merge

[ti-chi-bot]

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

Commit hash: 8fe6226

[codecov-commenter]

Codecov Report

Merging #5558 (61a327b) into master (fcea4d5) will increase coverage by 0.2866%.
The diff coverage is 61.4636%.

Flag	Coverage Δ
cdc	61.5349% <61.5661%> (+0.3868%)	⬆️
dm	51.9975% <61.2852%> (-0.0452%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

@@               Coverage Diff                @@
##             master      #5558        +/-   ##
================================================
+ Coverage   56.0768%   56.3635%   +0.2866%     
================================================
  Files           535        674       +139     
  Lines         70143      78636      +8493     
================================================
+ Hits          39334      44322      +4988     
- Misses        27078      30151      +3073     
- Partials       3731       4163       +432     

[ti-chi-bot]

@overvenus: Your PR was out of date, I have automatically updated it for you.

At the same time I will also trigger all tests for you:

/run-all-tests

If the CI test fails, you just re-trigger the test that failed and the bot will merge the PR for you after the CI passes.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the ti-community-infra/tichi repository.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5569.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5571.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5572.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5573.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5575.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5576.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5577.

[ti-chi-bot]

In response to a cherrypick label: new pull request created: #5578.