Fixes dependency install of env group Virtualization Host

Virtualization Host env group started failing for users with centos 7.4
and according to Ansible guide the correct format for env groups should
be "@^" prefix:

http://docs.ansible.com/ansible/latest/yum_module.html

JIRA: APEX-539

Change-Id: I3f71ce4462b33ad0772963869db4ea3c0f6e9e51
Signed-off-by: Tim Rozet <trozet@redhat.com>