During the investigation of WT-13157 (test_schema_abort failure), I identified an area for improvement in the thread_ckpt_run function.

Currently, the function continuously prints messages in a loop until the stable timestamp is set. In failure scenarios, these messages can clutter the logs, making it difficult to analyze the root cause.

This ticket proposes revising the logging behavior within thread_ckpt_run to:

• Reduce message verbosity in the failure case.
• Do not calculate the same difference time multiple times.