Change plugins_needs_config list format

Makes easier diff when adding or removing plugins.

roles/kubernetes/control-plane/vars/main.yaml

 ---
 # list of admission plugins that needs to be configured
-kube_apiserver_admission_plugins_needs_configuration: [EventRateLimit, PodSecurity]
+kube_apiserver_admission_plugins_needs_configuration:
+- EventRateLimit
+- PodSecurity