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: I60e24d1cd02dbb96b96325df4eb483eef0b6df83

tests/group_vars/all_containers.yml

@@ -13,8 +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/container1.yml

@@ -16,3 +16,4 @@
 ansible_host: 10.100.100.2
 ansible_become: True
 ansible_user: root
+container_name: container1

tests/host_vars/container2.yml

@@ -16,3 +16,4 @@
 ansible_host: 10.100.100.3
 ansible_become: True
 ansible_user: root
+container_name: container2

tests/host_vars/container3.yml

@@ -16,3 +16,4 @@
 ansible_host: 10.100.100.4
 ansible_become: True
 ansible_user: root
+container_name: container3