Remove deprecated apiserver-count kubeadm config option (#13262)

Signed-off-by: Ali Afsharzadeh <afsharzadeh8@gmail.com>

roles/kubernetes/control-plane/templates/kubeadm-config.v1beta4.yaml.j2

@@ -156,8 +156,6 @@ apiServer:
   - name: disable-admission-plugins
     value: "{{ kube_apiserver_disable_admission_plugins | join(',') }}"
 {% endif %}
-  - name: apiserver-count
-    value: "{{ kube_apiserver_count }}"
   - name: endpoint-reconciler-type
     value: lease
 {% if etcd_events_cluster_enabled %}