[Telemetry] Remove page-filter flag. (which is now user-filter)
[Telemetry] Remove page-filter flag. (which is now user-filter)

Review URL: https://codereview.chromium.org/1224983003

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#337750}

SummerLW/Perf-Insight-Report,benschmaus/catapult,catapult-project/catapult,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult-csm,catapult-project/catapult,sahiljain/catapult,SummerLW/Perf-Insight-Report,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult,benschmaus/catapult,SummerLW/Perf-Insight-Report,benschmaus/catapult,sahiljain/catapult,SummerLW/Perf-Insight-Report,benschmaus/catapult,catapult-project/catapult-csm,benschmaus/catapult,catapult-project/catapult-csm,catapult-project/catapult-csm,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult-csm,SummerLW/Perf-Insight-Report,SummerLW/Perf-Insight-Report,benschmaus/catapult,catapult-project/catapult,sahiljain/catapult,catapult-project/catapult-csm