Tweak log statement to reduce empty output

[Paultagoras]

Summary

• Turns out this message prints periodically when we have 0 records, but it probably shouldn't.

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided to include in CHANGELOG
• For significant changes, documentation in https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials