fix: Update logging test assertion

Updates an assert under `test_logging.py` to be more descriptive on
failure.

Signed-off-by: Jonathan Woollett-Light <jcawl@amazon.co.uk>

Author: Jonathan Woollett-Light

tests/integration_tests/functional/test_logging.py

@@ -59,7 +59,9 @@ def check_log_message_format(log_str, instance_id, level, show_level, show_origi
     pattern += "\\].*"
 
     mo = re.match(pattern, tag_and_msg)
-    assert mo is not None
+    assert (
+        mo is not None
+    ), f"Log message ({tag_and_msg}) does not match pattern ({pattern})."
 
     if show_level:
         tag_level = mo.group(3)