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-config.yml.j2

@@ -3,7 +3,7 @@ apiVersion: v1
 kind: ConfigMap
 metadata:
   name: coredns
-  namespace: {{ system_namespace }}
+  namespace: kube-system
   labels:
     addonmanager.kubernetes.io/mode: EnsureExists
 data: