[Telemetry] Set dummy variable regex in tools/telemetry and tools/perf This change sets Pylint's dummy-variables-rgx variable so that variable names consisting entirely of underscores will not trigger unused argument warnings. BUG=475714 R=dtu,aiolos,nednguyen@google.com Review URL: https://codereview.chromium.org/1114343003 Cr-Original-Commit-Position: refs/heads/master@{#357130} Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src Cr-Mirrored-Commit: 0ee5d1c3e7b926381f4662222cefbb4224d66d63 3 files changed