Update GRIT template as needed to create the default GKE cluster configuration

Overview

The scope of work for this issue is to modify or create a GRIT Terraform template specifically for creating a GKE cluster.

Note: The GRIT Terraform template required for the GCP + Google integration for setting up a runner on GKE is only to create the GKE cluster. The GitLab Runner Operator will install the Runner onto the GKE cluster.

Example - prior art

• GitLab Runner Terrform for an EKS cluster setup
• Terraform k8s-cluster-gke

Other points

• Review if there is any value in incorporating the Google Config Controller.

We have been using Config Connector and couldn’t be happier. In fact, we’re routinely impressed with the overall stability and the debuggability of our infrastructure. If you have existing patterns for templating and deploying Kubernetes YAML files, managing your infrastructure will be similar to managing your other service deployments. We leverage Config Connector extensively in our enterprise integration of GitLab and GCP called Konfig. Related blog post