Replace kube-master with kube_control_plane (#7256)

This replaces kube-master with kube_control_plane because of [1]:

  The Kubernetes project is moving away from wording that is
  considered offensive. A new working group WG Naming was created
  to track this work, and the word "master" was declared as offensive.
  A proposal was formalized for replacing the word "master" with
  "control plane". This means it should be removed from source code,
  documentation, and user-facing configuration from Kubernetes and
  its sub-projects.

NOTE: The reason why this changes it to kube_control_plane not
      kube-control-plane is for valid group names on ansible.

[1]: https://github.com/kubernetes/enhancements/blob/master/keps/sig-cluster-lifecycle/kubeadm/2067-rename-master-label-taint/README.md#motivation

scale.yml

@@ -2,6 +2,15 @@
 - name: Check ansible version
   import_playbook: ansible_version.yml
 
+- name: Add kube-master nodes to kube_control_plane
+  # This is for old inventory which contains kube-master instead of kube_control_plane
+  hosts: kube-master
+  gather_facts: false
+  tasks:
+    - name: add nodes to kube_control_plane group
+      group_by:
+        key: 'kube_control_plane'
+
 - hosts: bastion[0]
   gather_facts: False
   environment: "{{ proxy_disable_env }}"
@@ -32,8 +41,8 @@
     - { role: kubespray-defaults }
     - { role: etcd, tags: etcd, etcd_cluster_setup: false }
 
-- name: Download images to ansible host cache via first kube-master node
-  hosts: kube-master[0]
+- name: Download images to ansible host cache via first kube_control_plane node
+  hosts: kube_control_plane[0]
   gather_facts: False
   any_errors_fatal: "{{ any_errors_fatal | default(true) }}"
   environment: "{{ proxy_disable_env }}"
@@ -64,7 +73,7 @@
     - { role: kubernetes/node, tags: node }
 
 - name: Upload control plane certs and retrieve encryption key
-  hosts: kube-master | first
+  hosts: kube_control_plane | first
   environment: "{{ proxy_disable_env }}"
   gather_facts: False
   tags: kubeadm