branch_util: Add --skip-group-check flag

Service accounts cannot be added to mdb groups, so we need a way to
skip the MDB membership check.

BUG=b:177903295
TEST=go test

Change-Id: Ic61551fdb9272fe60508375c28fef74ecafba93b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/go/+/2705613
Reviewed-by: Julio Hurtado <juahurta@google.com>
Commit-Queue: Jack Neus <jackneus@google.com>
Tested-by: Jack Neus <jackneus@google.com>
Auto-Submit: Jack Neus <jackneus@google.com>
2 files changed