Improve debug_print to include timestamp, thread_id and reorder args in cppsuite.

The cppsuite debug_print utility function in test/cppsuite/test_harness/util/debug_utils.h can be improved a bit. These improvements are:

1. Reorder the arguments so log level is the first arg, making parsing easier.
2. Log the time and thread id at the front of the message. Find a nice format.