message: mb: Fully remove references to 'masters' in favor of 'builder_groups'.
  All of WebRTC's mb_configs should have been swapped over to using
  'builder_groups'.
  Cr-Commit-Position: refs/heads/master@{#32987}
diff: @@ -81,8 +81,6 @@ class MetaBuildWrapper(object):
  subp.add_argument('-b', '--builder',
  help='builder name to look up config from')
  subp.add_argument('-m', '--builder-group',
  - # TODO(crbug.com/1117773): Remove the 'master' args.
  - '--master',
  help='builder group name to look up config from')
  subp.add_argument('-c', '--config',
  help='configuration to analyze')
  