Log a warning if stoppage alert on test is not found.
Log a warning if stoppage alert on test is not found.

This is to fix the following error found in the logs:

AttributeError: 'NoneType' object has no attribute 'recovered'
(When adding new points in /add_point_queue).

Review URL: https://codereview.chromium.org/1726203004

catapult-project/catapult,catapult-project/catapult-csm,sahiljain/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,sahiljain/catapult,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,sahiljain/catapult,benschmaus/catapult,sahiljain/catapult,benschmaus/catapult,benschmaus/catapult,benschmaus/catapult,sahiljain/catapult,benschmaus/catapult,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult,benschmaus/catapult