Remove some unnecessary defaults from the rke config template

ansible/roles/rke_configuration/templates/cluster.yml.j2

@@ -25,9 +25,6 @@ nodes:
 services:
   etcd:
     image: ""
-    extra_args: {}
-    extra_binds: []
-    extra_env: []
     external_urls: []
     ca_cert: ""
     cert: ""
@@ -38,24 +35,15 @@ services:
     creation: ""
   kube-api:
     image: ""
-    extra_args: {}
-    extra_binds: []
-    extra_env: []
     service_cluster_ip_range: 10.43.0.0/16
     service_node_port_range: ""
     pod_security_policy: false
   kube-controller:
     image: ""
-    extra_args: {}
-    extra_binds: []
-    extra_env: []
     cluster_cidr: 10.42.0.0/16
     service_cluster_ip_range: 10.43.0.0/16
   scheduler:
     image: ""
-    extra_args: {}
-    extra_binds: []
-    extra_env: []
   kubelet:
     image: ""
 {% if flexvolume_plugins %}
@@ -63,20 +51,13 @@ services:
       volume-plugin-dir: /usr/libexec/kubernetes/kubelet-plugins/volume/exec
     extra_binds:
     - /usr/libexec/kubernetes/kubelet-plugins/volume/exec:/usr/libexec/kubernetes/kubelet-plugins/volume/exec
-{% else %}
-    extra_args: {}
-    extra_binds: []
 {% endif %}
-    extra_env: []
     cluster_domain: cluster.local
     infra_container_image: ""
     cluster_dns_server: 10.43.0.10
     fail_swap_on: false
   kubeproxy:
     image: ""
-    extra_args: {}
-    extra_binds: []
-    extra_env: []
 network:
   plugin: canal
   options: {}