control-plane: refactor group membership test

Testing with group_names does not require the groups to exist.

roles/kubernetes/control-plane/templates/kubeadm-config.v1beta3.yaml.j2

@@ -16,7 +16,7 @@ nodeRegistration:
 {% if kube_override_hostname | default('') %}
   name: "{{ kube_override_hostname }}"
 {% endif %}
-{% if inventory_hostname in groups['kube_control_plane'] and inventory_hostname not in groups['kube_node'] %}
+{% if 'kube_control_plane' in group_names and 'kube_node' not in group_names %}
   taints:
   - effect: NoSchedule
     key: node-role.kubernetes.io/control-plane

roles/kubernetes/control-plane/templates/kubeadm-controlplane.v1beta3.yaml.j2

@@ -24,7 +24,7 @@ controlPlane:
 nodeRegistration:
   name: {{ kube_override_hostname | default(inventory_hostname) }}
   criSocket: {{ cri_socket }}
-{% if inventory_hostname in groups['kube_control_plane'] and inventory_hostname not in groups['kube_node'] %}
+{% if 'kube_control_plane' in group_names and 'kube_node' not in group_names %}
   taints:
   - effect: NoSchedule
     key: node-role.kubernetes.io/control-plane