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/download/tasks/prep_kubeadm_images.yml

@@ -38,7 +38,6 @@
   shell: "set -o pipefail && {{ bin_dir }}/kubeadm config images list --config={{ kube_config_dir }}/kubeadm-images.yaml | grep -Ev 'coredns|pause'"
   args:
     executable: /bin/bash
-  environment: "{{ proxy_disable_env }}"
   register: kubeadm_images_raw
   run_once: true
   changed_when: false