[dashboard] Do not use --story-filter on webrtc.* benchmarks
[dashboard] Do not use --story-filter on webrtc.* benchmarks

Most webrtc benchmarks have a single story, and the story name is not
always easy to guess from the metric name.

BUG=catapult:#3107

Review-Url: https://codereview.chromium.org/2617473002

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