After Trace#limit, we seek to the next line in case

What does this MR do?

Make the trace read less than LIMIT_SIZE, by seeking to the next newline. This is still possible to cut into something, but much unlikely to happen. For traces having long lines, we could be discarding too much. We could deal with that in the next iteration.

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests
  • Added for this feature/bug

What are the relevant issue numbers?

Closes #30796 (closed)