MNAIO: Do not use apt-cacher-ng on the MNAIO host

If all VM's are down, then the IP Address that apt-cacher-ng is
listening on will also be down, resulting in the host not being
capable of reaching it for any apt activities.

Rather than try to work around this, we simply let the host access
its upstream repositories directly given that the cache is primarily
for the purpose of speeding up the VM deployment.

Change-Id: I12f474321e9a9302d361907a882051c963ccf045

multi-node-aio/playbooks/deploy-acng.yml

@@ -89,15 +89,6 @@
       notify:
         - reload acng
 
-    - name: Drop apt package manager proxy
-      copy:
-        content: 'Acquire::http { Proxy "{{ default_ubuntu_mirror_proxy }}"; };'
-        dest: "/etc/apt/apt.conf.d/00apt-cacher-proxy"
-
-    - name: Update apt when proxy is added
-      apt:
-        update_cache: yes
-
   handlers:
     - name: reload acng
       service: