[update-checkout] fix final line cleanup

Author: charles-zablit

utils/update_checkout/update_checkout/parallel_runner.py

@@ -113,7 +113,7 @@ def _monitor(self):
 
             time.sleep(self._monitor_polling_period)
 
-        sys.stdout.write("\r" + " " * len(last_output) + "\r\n")
+        sys.stdout.write("\r" + " " * self._terminal_width + "\r")
         sys.stdout.flush()
 
     @staticmethod