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

roles/kubernetes/kubeadm/tasks/kubeadm_etcd_node.yml

@@ -1,7 +1,7 @@
 ---
 - name: Parse certificate key if not set
   set_fact:
-    kubeadm_certificate_key: "{{ hostvars[groups['kube-master'][0]]['kubeadm_certificate_key'] }}"
+    kubeadm_certificate_key: "{{ hostvars[groups['kube_control_plane'][0]]['kubeadm_certificate_key'] }}"
   when: kubeadm_certificate_key is undefined
 
 - name: Pull control plane certs down

roles/kubernetes/kubeadm/tasks/main.yml

@@ -25,7 +25,7 @@
     get_checksum: no
     get_mime: no
   register: kubeadm_ca_stat
-  delegate_to: "{{ groups['kube-master'][0] }}"
+  delegate_to: "{{ groups['kube_control_plane'][0] }}"
   run_once: true
 
 - name: Calculate kubeadm CA cert hash
@@ -36,14 +36,14 @@
   when:
     - kubeadm_ca_stat.stat is defined
     - kubeadm_ca_stat.stat.exists
-  delegate_to: "{{ groups['kube-master'][0] }}"
+  delegate_to: "{{ groups['kube_control_plane'][0] }}"
   run_once: true
   changed_when: false
 
 - name: Create kubeadm token for joining nodes with 24h expiration (default)
   command: "{{ bin_dir }}/kubeadm token create"
   register: temp_token
-  delegate_to: "{{ groups['kube-master'][0] }}"
+  delegate_to: "{{ groups['kube_control_plane'][0] }}"
   when: kubeadm_token is not defined
   changed_when: false
 
@@ -118,7 +118,7 @@
   args:
     executable: /bin/bash
   run_once: true
-  delegate_to: "{{ groups['kube-master']|first }}"
+  delegate_to: "{{ groups['kube_control_plane']|first }}"
   delegate_facts: false
   when:
     - kubeadm_config_api_fqdn is not defined
@@ -138,7 +138,7 @@
 - name: Restart all kube-proxy pods to ensure that they load the new configmap
   command: "{{ bin_dir }}/kubectl --kubeconfig {{ kube_config_dir }}/admin.conf delete pod -n kube-system -l k8s-app=kube-proxy --force --grace-period=0"
   run_once: true
-  delegate_to: "{{ groups['kube-master']|first }}"
+  delegate_to: "{{ groups['kube_control_plane']|first }}"
   delegate_facts: false
   when:
     - kubeadm_config_api_fqdn is not defined
@@ -151,6 +151,6 @@
   include_tasks: kubeadm_etcd_node.yml
   when:
     - etcd_kubeadm_enabled
-    - inventory_hostname not in groups['kube-master']
+    - inventory_hostname not in groups['kube_control_plane']
     - kube_network_plugin in ["calico", "flannel", "canal", "cilium"] or cilium_deploy_additionally | default(false) | bool
     - kube_network_plugin != "calico" or calico_datastore == "etcd"