Fix proxy usage when *_PROXY are present in environment (#7309)

Since a790935d02 all proxy users
should be properly configured

Now when you have *_PROXY vars in your environment it can leads to failure
if NO_PROXY is not correct, or to persistent configuration changes
as seen with kubeadm in 1c5391dda7

Instead of playing constant whack-a-bug, inject empty *_PROXY vars everywhere
at the play level, and override at the task level when needed

Signed-off-by: Etienne Champetier <e.champetier@ateme.com>
(cherry picked from commit 067db686f6)

roles/kubernetes/master/tasks/kubeadm-fix-apiserver.yml

@@ -20,7 +20,6 @@
     {{ bin_dir }}/kubeadm init phase kubeconfig all
     --config {{ kube_config_dir }}/kubeadm-config.yaml
     --kubeconfig-dir {{ kubeconfig_temp_dir.path }}
-  environment: "{{ proxy_disable_env }}"
   when: kubeconfig_correct_apiserver.rc != 0
 
 - name: Copy new kubeconfigs to kube config dir