[TBMv2] Add test for adding value from dict with sample diagnostic
[TBMv2] Add test for adding value from dict with sample diagnostic

This covers the code path fixed in https://codereview.chromium.org/2284173002

BUG=catapult:#2729

Review-Url: https://codereview.chromium.org/2288943002

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