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/network_plugin/calico/tasks/pre.yml

@@ -19,7 +19,7 @@
 
 - name: Calico | Get kubelet hostname
   shell: >-
-    set -o pipefail && {{ bin_dir }}/kubectl get node -o custom-columns='NAME:.metadata.name,INTERNAL-IP:.status.addresses[?(@.type=="InternalIP")].address'
+    set -o pipefail && {{ kubectl }} get node -o custom-columns='NAME:.metadata.name,INTERNAL-IP:.status.addresses[?(@.type=="InternalIP")].address'
     | egrep "{{ ansible_all_ipv4_addresses | join('$|') }}$" | cut -d" " -f1
   args:
     executable: /bin/bash

roles/network_plugin/calico/tasks/typha_certs.yml

@@ -1,6 +1,6 @@
 ---
 - name: Calico | Check if typha-server exists
-  command: "{{ bin_dir }}/kubectl -n kube-system get secret typha-server"
+  command: "{{ kubectl }} -n kube-system get secret typha-server"
   register: typha_server_secret
   changed_when: false
   failed_when: false
@@ -35,7 +35,7 @@
 
 - name: Calico | Create typha tls secrets
   command: >-
-    {{ bin_dir }}/kubectl -n kube-system
+    {{ kubectl }} -n kube-system
     create secret tls {{ item.name }}
     --cert {{ item.cert }}
     --key {{ item.key }}