Stop templating kube-system namespace and creating it (#2545)

Kubernetes makes this namespace automatically, so there is
no need for kubespray to manage it.

roles/kubernetes-apps/ansible/templates/coredns-clusterrolebinding.yml.j2

@@ -15,4 +15,4 @@ roleRef:
 subjects:
 - kind: ServiceAccount
   name: coredns
-  namespace: {{ system_namespace }}
+  namespace: kube-system