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-apps/external_cloud_controller/vsphere/tasks/main.yml

@@ -9,7 +9,7 @@
     mode: 0640
   with_items:
     - external-vsphere-cpi-cloud-config
-  when: inventory_hostname == groups['kube-master'][0]
+  when: inventory_hostname == groups['kube_control_plane'][0]
   tags: external-vsphere
 
 - name: External vSphere Cloud Controller | Generate Manifests
@@ -22,20 +22,20 @@
     - external-vsphere-cloud-controller-manager-role-bindings.yml
     - external-vsphere-cloud-controller-manager-ds.yml
   register: external_vsphere_manifests
-  when: inventory_hostname == groups['kube-master'][0]
+  when: inventory_hostname == groups['kube_control_plane'][0]
   tags: external-vsphere
 
 - name: External vSphere Cloud Provider Interface | Create a CPI configMap manifest
   command: "{{ bin_dir }}/kubectl create configmap cloud-config --from-file=vsphere.conf={{ kube_config_dir }}/external-vsphere-cpi-cloud-config -n kube-system --dry-run --save-config -o yaml"
   register: external_vsphere_configmap_manifest
-  when: inventory_hostname == groups['kube-master'][0]
+  when: inventory_hostname == groups['kube_control_plane'][0]
   tags: external-vsphere
 
 - name: External vSphere Cloud Provider Interface | Apply a CPI configMap manifest
   command:
     cmd: "{{ bin_dir }}/kubectl apply -f -"
     stdin: "{{ external_vsphere_configmap_manifest.stdout }}"
-  when: inventory_hostname == groups['kube-master'][0]
+  when: inventory_hostname == groups['kube_control_plane'][0]
   tags: external-vsphere
 
 - name: External vSphere Cloud Controller | Apply Manifests
@@ -46,7 +46,7 @@
   with_items:
     - "{{ external_vsphere_manifests.results }}"
   when:
-    - inventory_hostname == groups['kube-master'][0]
+    - inventory_hostname == groups['kube_control_plane'][0]
     - not item is skipped
   loop_control:
     label: "{{ item.item }}"