builder_configs: drop id.branch

This field is an unused carry-over from cbuildbot (which branch of
chromite to checkout when starting the recipe.)

BUG=None
TEST=generate

Cq-Depend: chromium:2794879, chrome-internal:3722470
Change-Id: Ib8b176ca07a6e46edc8a94fbcc06ff1e50ac4c15
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2795273
Reviewed-by: George Engelbrecht <engeg@google.com>
Commit-Queue: LaMont Jones <lamontjones@chromium.org>
2 files changed