Remove CQ for unsupported branch chrome/m115

Change-Id: Id0a45a6d37156aa6b45056093c640a14a536cf48
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/762277
Reviewed-by: Heather Miller <hcm@google.com>
Reviewed-by: Kevin Lubick <kjlubick@google.com>