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/pre-remove/tasks/main.yml

@@ -1,7 +1,7 @@
 ---
 - name: remove-node | List nodes
   command: >-
-    {{ bin_dir }}/kubectl get nodes -o go-template={% raw %}'{{ range .items }}{{ .metadata.name }}{{ "\n" }}{{ end }}'{% endraw %}
+    {{ kubectl }} get nodes -o go-template={% raw %}'{{ range .items }}{{ .metadata.name }}{{ "\n" }}{{ end }}'{% endraw %}
   register: nodes
   delegate_to: "{{ groups['kube_control_plane']|first }}"
   changed_when: false
@@ -9,7 +9,7 @@
 
 - name: remove-node | Drain node except daemonsets resource  # noqa 301
   command: >-
-    {{ bin_dir }}/kubectl --kubeconfig {{ kube_config_dir }}/admin.conf drain
+    {{ kubectl }} drain
       --force
       --ignore-daemonsets
       --grace-period {{ drain_grace_period }}