Allow specificity for GKE Cluster Location

What does this MR do?

Improves resiliency of create_project_with_auto_devops_spec.rb in light of the recent GKE errors we've been seeing from running this spec.

Allows qa/service/kubernetes_cluster.rb to support a new var GCLOUD_REGION.

TODO:

• Replace GCLOUD_ZONE with GCLOUD_REGION for quality group https://gitlab.com/groups/gitlab-org/quality/-/settings/ci_cd

Allow specificity for GKE Cluster Location

GCLOUD_REGION and GCLOUD_ZONE are both valid locations for creating clusters. Specifying GCLOUD_ZONE is more specific, therefore will choose ZONE over REGION.

Add --num-nodes defaulting to 3. When prov- isioning a cluster by region, the number is multiplied.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance and testing

When specifying GCLOUD_REGION over GCLOUD_ZONE, it's important to know that the default number of nodes is 3. There are 4 zones within us-central1. If GCLOUD_NUM_NODES isn't specified, there will be 3·4=12 in the cluster.

It should be known that after this is merged, we might incur more costs if we don't specify --num-nodes as there would be 3·4=12 nodes in the cluster.