Merge branch 'qa-gke-cluster-10gb' into 'master'

QA spec for Auto DevOps should use 10GB GKE disk

See merge request gitlab-org/gitlab-ce!31266

qa/qa/service/kubernetes_cluster.rb

@@ -29,6 +29,7 @@ module QA
           #{auth_options}
           --enable-basic-auth
           --region #{Runtime::Env.gcloud_region}
+          --disk-size 10GB
           && gcloud container clusters
           get-credentials
           --region #{Runtime::Env.gcloud_region}