builder_config: Property to indicate which manifest to sync to.

Currently all builders sync to the internal manifest, public builders
should use the external one.

BUG=chromium:1009192
TEST=./generate.sh

Change-Id: I85499b571a820f9d472f03ad815719224b13e8b1
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2332886
Commit-Queue: Navil Perez <navil@google.com>
Tested-by: Navil Perez <navil@google.com>
Reviewed-by: LaMont Jones <lamontjones@chromium.org>
2 files changed