Clean up container cache prep in tasks

This patch cleans up the container cache preparation in the tests
due to the following patches:

- https://review.openstack.org/307856 (new image build process)
- https://review.openstack.org/315114 (new apt config process)
- https://review.openstack.org/322188 (new resolver config process)

Change-Id: I3ce8ce07297d456e7f642c09578d92a07f579162

tests/test-prepare-host.yml

@@ -31,31 +31,12 @@
       stat:
         path: /etc/nodepool/provider
       register: nodepool
-    - name: Set the files to copy into the container cache for OpenStack-CI instances (deb)
-      set_fact:
-        lxc_container_cache_files:
-          - { src: '/etc/pip.conf', dest: '/etc/pip.conf' }
-          - { src: '/etc/apt/apt.conf.d/99unauthenticated', dest: '/etc/apt/apt.conf.d/99unauthenticated' }
-      when:
-        - nodepool.stat.exists | bool
-        - ansible_pkg_mgr == 'apt'
-    - name: Set the files to copy into the container cache for OpenStack-CI instances (rpm)
+    - name: Set the files to copy into the container cache for OpenStack-CI instances
       set_fact:
         lxc_container_cache_files:
           - { src: '/etc/pip.conf', dest: '/etc/pip.conf' }
       when:
         - nodepool.stat.exists | bool
-        - ansible_pkg_mgr == 'yum'
-    - name: Determine the existing Ubuntu repo configuration
-      shell: 'awk "/^deb .*ubuntu\/? {{ ansible_distribution_release }} main/ {print \$2; exit}" /etc/apt/sources.list'
-      register: ubuntu_repo
-      changed_when: false
-      when: ansible_pkg_mgr == 'apt'
-    - name: Set apt repo facts based on discovered information
-      set_fact:
-        lxc_container_template_main_apt_repo: "{{ ubuntu_repo.stdout }}"
-        lxc_container_template_security_apt_rep: "{{ ubuntu_repo.stdout }}"
-      when: ansible_pkg_mgr == 'apt'
   roles:
     - role: "lxc_hosts"
       lxc_net_address: 10.100.100.1