Modify cluster creation API method to enable legacy_apac as default

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

app/services/clusters/gcp/finalize_creation_service.rb

@@ -30,10 +30,10 @@ module Clusters
           ca_cert: Base64.decode64(gke_cluster.master_auth.cluster_ca_certificate),
           username: gke_cluster.master_auth.username,
           password: gke_cluster.master_auth.password,
-          token: request_kuberenetes_token)
+          token: request_kubernetes_token)
       end
-      def request_kuberenetes_token
+      def request_kubernetes_token
         Ci::FetchKubernetesTokenService.new(
           'https://' + gke_cluster.endpoint,
           Base64.decode64(gke_cluster.master_auth.cluster_ca_certificate),

changelogs/unreleased/41619-turn-on-legacy-authorization-for-new-clusters-on-gke.yml

+---
+title: Enable Legacy Authorization by default on Cluster creations
+merge_request: 17302
+author:
+type: fixed

lib/google_api/cloud_platform/client.rb

@@ -76,9 +76,13 @@ module GoogleApi
               "initial_node_count": cluster_size,
               "node_config": {
                 "machine_type": machine_type
+              },
+              "legacy_abac": {
+                "enabled": true
               }
             }
-          } )
+          }
+        )
         service.create_cluster(project_id, zone, request_body, options: user_agent_header)
       end

spec/lib/google_api/cloud_platform/client_spec.rb

@@ -115,6 +115,9 @@ describe GoogleApi::CloudPlatform::Client do
               "initial_node_count": cluster_size,
               "node_config": {
                 "machine_type": machine_type
+              },
+              "legacy_abac": {
+                "enabled": true
               }
             }
           } )