Switch `use_stemcell` to be the primary stemcell
Switch `use_stemcell` to be the primary stemcell

- We added `use_stemcell` to the no-op job thinking it was a safe way to
  exercise the 0 instance behavior. However, our system specs explicitly
  set the no-op job to 2 instances. Thus, we've temporarily set it to be
  the same as the primary stemcell so that these specs don't have to be
  rewritten to upload a second stemcell.

Signed-off-by: Kashyap Vedurmudi <8989af17c4735185a29fa1b2a00cb8c0b2ca8b22@pivotal.io>

pivotal-cf-experimental/ops-manager-example,pivotal-cf-experimental/ops-manager-example,pivotal-cf-experimental/ops-manager-example,pivotal-cf-experimental/ops-manager-example