Lower log level for DUT type file doesn't exist (#16119) (#16129)

Co-authored-by: bingwang-ms <66248323+bingwang-ms@users.noreply.github.com>

tests/ptf_runner.py

@@ -42,7 +42,7 @@ def get_dut_type(host):
         else:
             logger.warning("DUT type file is empty.")
     else:
-        logger.warning("DUT type file doesn't exist.")
+        logger.info("DUT type file doesn't exist.")
     return "Unknown"