This removes every reference but the "--master/-m" cmd-line arg and the
"masters" mb_config.pyl key, which will be removed in a follow-up once
all users of mb.py (ie: recipes) have switched over.
"builder_group" is also the term we're using when replacing "master" in
recipe code: crbug.com/1109276. So we should conform on using that term
going forward.
Bug: chromium:1117773
Change-Id: I1de1b8e68bcf2c9d68b00a05f0f5761cf8b4ef9a
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/201382
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Cr-Commit-Position: refs/heads/master@{#32964}