Use a variable for standardizing kubectl invocation (#8329)

* Add kubectl variable

* Replace kubectl usage by kubectl variable in roles

* Remove redundant --kubeconfig on kubectl usage

* Replace unecessary shell usage with command

roles/recover_control_plane/control-plane/tasks/main.yml

@@ -1,6 +1,6 @@
 ---
 - name: Wait for apiserver
-  command: "{{ bin_dir }}/kubectl get nodes"
+  command: "{{ kubectl }} get nodes"
   environment:
     - KUBECONFIG: "{{ ansible_env.HOME | default('/root') }}/.kube/config"
   register: apiserver_is_ready
@@ -11,7 +11,7 @@
   when: groups['broken_kube_control_plane']
 
 - name: Delete broken kube_control_plane nodes from cluster
-  command: "{{ bin_dir }}/kubectl delete node {{ item }}"
+  command: "{{ kubectl }} delete node {{ item }}"
   environment:
     - KUBECONFIG: "{{ ansible_env.HOME | default('/root') }}/.kube/config"
   with_items: "{{ groups['broken_kube_control_plane'] }}"