Fix nodeselectors for contiv and nginx-ingress (#4662)

* Fix nodeselectors for contiv and nginx-ingress

Change-Id: Ib3eb6bd87193c69a90ee944c9164a0b6792c79ba

* Set kube proxy mode to iptables for addons task

Change-Id: Iff71a71f672405c74b4708c71db15ddc4391a53a

roles/network_plugin/contiv/templates/contiv-etcd-proxy.yml.j2

@@ -20,8 +20,13 @@ spec:
 {% endif %}
       hostNetwork: true
       hostPID: true
-      nodeSelector:
-        node-role.kubernetes.io/node: ""
+      affinity:
+       nodeAffinity:
+         requiredDuringSchedulingIgnoredDuringExecution:
+           nodeSelectorTerms:
+           - matchExpressions:
+             - key: node-role.kubernetes.io/master
+               operator: DoesNotExist
       containers:
         - name: contiv-etcd-proxy
           image: {{ contiv_etcd_image_repo }}:{{ contiv_etcd_image_tag }}