ci: use a container client VM

The client won't run on centos7 anymore but on Atomic host just like the
rest of the daemons.

Signed-off-by: Sébastien Han <seb@redhat.com>

tests/functional/centos/7/docker/hosts

@@ -19,7 +19,7 @@ rgw0
 nfs0
 
 [clients]
-client0 ceph_origin="repository" ceph_repository="community"
+client0
 
 [rbdmirrors]
 rbd-mirror0

tests/functional/centos/7/docker/vagrant_variables.yml

@@ -46,7 +46,7 @@ disks: "[ '/dev/sda', '/dev/sdb' ]"
 #   - https://atlas.hashicorp.com/boxes/search?utf8=✓&sort=&provider=virtualbox&q=
 #   - https://download.gluster.org/pub/gluster/purpleidea/vagrant/
 vagrant_box: centos/atomic-host
-client_vagrant_box: centos/7
+#client_vagrant_box: centos/7
 #ssh_private_key_path: "~/.ssh/id_rsa"
 # The sync directory changes based on vagrant box
 # Set to /home/vagrant/sync for Centos/7, /home/{ user }/vagrant for openstack and defaults to /vagrant