(#42643)

GKE 1.8 has RBAC on by default, since GKE has bumped the default version
to 1.8.7 RBAC is now on, and we don't support that out of the box.

This was also avoiding cluster applications (tiller, prometheus, etc), to
be installed.

Closes #41619

Fix out of sync with KubernetesService. Remove namespace pramas from controller. Use time_with_zone in schema. Remove Gcp::Clusters from safe_model_attributes.ym