Set container_name as host_var in test inventory

The connection plugin no longer falls back on using the
inventory_hostname as the container_name. Set container_name as a host
var for each container in the test inventory.

Change-Id: I4e76e65b8e2b4b0968f8e5af89e08da4dd69eb9b

tests/group_vars/all_containers.yml

@@ -13,7 +13,6 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-container_name: "{{ inventory_hostname }}"
 container_networks:
   management_address:
     address: "{{ ansible_host }}"

tests/host_vars/infra1.yml

@@ -17,3 +17,4 @@ ansible_host: 10.1.1.101
 ansible_become: True
 ansible_user: root
 tunnel_address: 10.1.2.101
+container_name: infra1

tests/host_vars/openstack1.yml

@@ -22,3 +22,4 @@ ansible_become: True
 ansible_user: root
 tunnel_address: 10.1.2.102
 neutron_local_ip: 10.1.2.102
+container_name: openstack1