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

contrib/network-storage/glusterfs/glusterfs.yml

@@ -19,6 +19,6 @@
   roles:
     - { role: glusterfs/client }
 
-- hosts: kube-master[0]
+- hosts: kube_control_plane[0]
   roles:
     - { role: kubernetes-pv }

contrib/network-storage/glusterfs/inventory.example

@@ -14,7 +14,7 @@
 # gfs_node2 ansible_ssh_host=95.54.0.19 # disk_volume_device_1=/dev/vdc  ip=10.3.0.8 
 # gfs_node3 ansible_ssh_host=95.54.0.20 # disk_volume_device_1=/dev/vdc  ip=10.3.0.9 
 
-# [kube-master]
+# [kube_control_plane]
 # node1
 # node2
 
@@ -32,7 +32,7 @@
 
 # [k8s-cluster:children]
 # kube-node
-# kube-master
+# kube_control_plane
 
 # [gfs-cluster]
 # gfs_node1

contrib/network-storage/glusterfs/roles/kubernetes-pv/ansible/tasks/main.yaml

@@ -8,7 +8,7 @@
     - { file: glusterfs-kubernetes-pv.yml.j2, type: pv, dest: glusterfs-kubernetes-pv.yml}
     - { file: glusterfs-kubernetes-endpoint-svc.json.j2, type: svc, dest: glusterfs-kubernetes-endpoint-svc.json}
   register: gluster_pv
-  when: inventory_hostname == groups['kube-master'][0] and groups['gfs-cluster'] is defined and hostvars[groups['gfs-cluster'][0]].gluster_disk_size_gb is defined
+  when: inventory_hostname == groups['kube_control_plane'][0] and groups['gfs-cluster'] is defined and hostvars[groups['gfs-cluster'][0]].gluster_disk_size_gb is defined
 
 - name: Kubernetes Apps | Set GlusterFS endpoint and PV
   kube:
@@ -19,4 +19,4 @@
     filename: "{{ kube_config_dir }}/{{ item.item.dest }}"
     state: "{{ item.changed | ternary('latest','present') }}"
   with_items: "{{ gluster_pv.results }}"
-  when: inventory_hostname == groups['kube-master'][0] and groups['gfs-cluster'] is defined
+  when: inventory_hostname == groups['kube_control_plane'][0] and groups['gfs-cluster'] is defined

contrib/network-storage/heketi/heketi-tear-down.yml

@@ -1,5 +1,5 @@
 ---
-- hosts: kube-master[0]
+- hosts: kube_control_plane[0]
   roles:
     - { role: tear-down }
 

contrib/network-storage/heketi/heketi.yml

@@ -3,7 +3,7 @@
   roles:
     - { role: prepare }
 
-- hosts: kube-master[0]
+- hosts: kube_control_plane[0]
   tags:
     - "provision"
   roles:

contrib/network-storage/heketi/inventory.yml.sample

@@ -7,7 +7,7 @@ all:
             vars:
                 kubelet_fail_swap_on: false
             children:
-                kube-master:
+                kube_control_plane:
                     hosts:
                         node1:
                 etcd: