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/network_plugin/contiv/templates/contiv-netplugin-serviceaccount.yml.j2

@@ -2,6 +2,6 @@ apiVersion: v1
 kind: ServiceAccount
 metadata:
   name: contiv-netplugin
-  namespace: {{ system_namespace }}
+  namespace: kube-system
   labels:
     kubernetes.io/cluster-service: "true"