Bug#930367: cloud.debian.org: vagrant images: use systemd-networkd for virtualbox provider

[Nicolas Quiniou-Briand <nqb@azyx.fr>]

Package: cloud.debian.org
Severity: normal

Dear Maintainer,

I noticed a difference between providers for the same box 
(debian/stretch64):

* with libvirt provider, `systemd-networkd` service is enabled and started
after first boot of VM.

* with virtualbox provider, `systemd-networkd`
service is disabled and stopped after first boot of VM.

It will be better to have only one way to manage network for the same 
image with different providers.