GitLab

MB was originally intended to be used to manage non-bot configs
as well, but we ended up not using this. This CL removes a bunch
of associated code that was hence no longer needed.

R=jbudorick@chromium.org, kjellander@chromium.org
BUG=

Review URL: https://codereview.chromium.org/1808093002

Cr-Commit-Position: refs/heads/master@{#381818}