tcTests: bridge deleted before downed

Change-Id: I485932d45cce01eef7be2cceb19f66d9aa3a03b5
Signed-off-by: Petr Horáček <phoracek@redhat.com>
Reviewed-on: http://gerrit.ovirt.org/36130
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Tested-by: Dan Kenigsberg <danken@redhat.com>