Added some logging to run_dev_server_tests to help narrow down flakiness.
Added some logging to run_dev_server_tests to help narrow down flakiness.

Review URL: https://codereview.chromium.org/1301893004

benschmaus/catapult,benschmaus/catapult,scottmcmaster/catapult,modulexcite/catapult,SummerLW/Perf-Insight-Report,modulexcite/catapult,catapult-project/catapult,catapult-project/catapult-csm,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult-csm,sahiljain/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult-csm,catapult-project/catapult,scottmcmaster/catapult,zeptonaut/catapult,benschmaus/catapult,0x90sled/catapult,SummerLW/Perf-Insight-Report,zeptonaut/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult,benschmaus/catapult,SummerLW/Perf-Insight-Report,catapult-project/catapult-csm,scottmcmaster/catapult,sahiljain/catapult,catapult-project/catapult,0x90sled/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult-csm,sahiljain/catapult,0x90sled/catapult,catapult-project/catapult,benschmaus/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,modulexcite/catapult,zeptonaut/catapult,benschmaus/catapult