Move CNI config and add MTU support for calico-cni

- Move CNI configuration creation for Calico to appropriate
network_plugin role from kubernetes/node.
- Add support for MTU configuration in Calico.

roles/network_plugin/calico/tasks/main.yml

@@ -1,4 +1,10 @@
 ---
+- name: Calico | Write Calico cni config
+  template:
+    src: "cni-calico.conf.j2"
+    dest: "/etc/cni/net.d/10-calico.conf"
+    owner: kube
+
 - name: Calico | Set docker daemon options
   template:
     src: docker