Remove lxc_container_bind_mounts in test group_vars

The value set in this var is already set as part of
lxc_container_default_bind_mounts in the tests repo
test-vars.yml so it's redundant.

Change-Id: I48c0ffb8f95b30fabcdeba0c740bc2e737960c6f

tests/group_vars/all_containers.yml

@@ -24,6 +24,3 @@ container_networks:
 physical_host: localhost
 properties:
   service_name: "{{ inventory_hostname }}"
-lxc_container_bind_mounts:
-  - host_directory: "/openstack/log/{{ inventory_hostname }}"
-    container_directory: "/var/log"