raspberry64: networks: Connections are set to default after reboot

https://discuss.freedombox.org/t/samba-and-cockpit-doesnt-work-well-with-raspberry-pi-4-model-b/1982/13?u=nbenedek

The advice from the Debian Wiki fixes the issue:

FreedomBox uses NetworkManager to manage network configuration. If you have configured your network interfaces using Debian installer or by editing /etc/network/interfaces, FreedomBox will not manage those interfaces. (See bug #797614.) To let FreedomBox/NetworkManager manage your network interfaces, edit the /etc/network/interfaces manually and ensure that it contains only the following:

auto lo

iface lo inet loopback_