tox: use the vagrant-libvirt management network

Instead of specifying the registry address for each ceph-ansible scenario
on the dedicated public network (which is different) we can use the
vagrant-libvirt management network that is common to all scenarios.

https://github.com/vagrant-libvirt/vagrant-libvirt#management-network

Signed-off-by: Dimitri Savineau <dsavinea@redhat.com>
(cherry picked from commit 072de56)

tox.ini

@@ -21,9 +21,7 @@ setenv=
   all_daemons: CEPH_ANSIBLE_SCENARIO_PATH = {toxinidir}/ceph-ansible/tests/functional/all_daemons/container
   collocation: CEPH_ANSIBLE_SCENARIO_PATH = {toxinidir}/ceph-ansible/tests/functional/collocation/container
   lvm_osds: CEPH_ANSIBLE_SCENARIO_PATH = {toxinidir}/ceph-ansible/tests/functional/lvm-osds/container
-  all_daemons: REGISTRY_ADDRESS = 192.168.17.1:5000
-  collocation: REGISTRY_ADDRESS = 192.168.15.1:5000
-  lvm_osds: REGISTRY_ADDRESS = 192.168.39.1:5000
+  REGISTRY_ADDRESS = 192.168.121.1:5000
   CEPH_ANSIBLE_BRANCH = stable-3.2
   VAGRANT_PROVIDER = {env:VAGRANT_PROVIDER:libvirt}
   CEPH_ANSIBLE_VAGRANT_BOX = centos/atomic-host