Move to the new configs only and remove the old ones from the
scheduler, milo and buildbucket config files.

Bug: 833999
Change-Id: I26c2ef619c220ef08ecc8654e5727c1f89987ca7
Reviewed-on: https://chromium-review.googlesource.com/1053062Reviewed-by: Jamie Madill <jmadill@chromium.org>
Reviewed-by: Frank Henigman <fjhenigman@chromium.org>
Commit-Queue: Jamie Madill <jmadill@chromium.org>