contrib: Fix cleanup of libvirt data
contrib: Fix cleanup of libvirt data

Following instructions from:
https://docs.docker.com/compose/environment-variables/#/passing-environment-variables-through-to-containers

Mirantis/virtlet,vefimova/virtlet,vefimova/virtlet,vefimova/virtlet,nhlfr/virtlet,nhlfr/virtlet,vefimova/virtlet,nhlfr/virtlet,Mirantis/virtlet,nhlfr/virtlet