Rename master to control plane - non-breaking changes only (#11394)

K8s is moving away from the "master" terminology, so kubespray should follow the same naming conventions. See https://github.com/kubernetes/community/blob/65d886bb3029e73d9729e1d4f27422a7985233ed/sig-architecture/naming/recommendations/001-master-control-plane.md

playbooks/remove_node.yml

@@ -33,7 +33,7 @@
     - { role: remove-node/remove-etcd-node }
     - { role: reset, tags: reset, when: reset_nodes | default(True) | bool }
 
-# Currently cannot remove first master or etcd
+# Currently cannot remove first control plane node or first etcd node
 - name: Post node removal
   hosts: "{{ node | default('kube_control_plane[1:]:etcd[1:]') }}"
   gather_facts: false