Remove support for creating non-RBAC kubernetes clusters
Problem to solve
Currently, users are offered the option to create a non-RBAC k8s cluster. This is counter to current k8s best practices and gives room for error when used in conjunction with other services (ie knative)
On cluster creation, remove the
RBAC-enabled cluster option, so that all clusters are created with RBAC enabled by default. If user wishes to remove rbac they can still do so from the command line.