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/remove-node/post-remove/tasks/main.yml

@@ -1,6 +1,6 @@
 ---
 - name: Delete node
-  command: "{{ bin_dir }}/kubectl delete node {{ kube_override_hostname|default(inventory_hostname) }}"
+  command: "{{ kubectl }} delete node {{ kube_override_hostname|default(inventory_hostname) }}"
   delegate_to: "{{ groups['kube_control_plane']|first }}"
   when: inventory_hostname in groups['k8s_cluster']
   retries: 10