vm-configurator: Rework logic for when we recreate network interface

In commit 8a336ba0 we started to recreate the network interface only
when the bridge was available and the existing domain network interface
was "user".

That's correct but we also should recreate the network interface when
there isn't a bridge available and the existing domain network interface
was "bridge".

This fixes the issue of when the virbr0 network interface was availale
during the VM creation but is no longer available afterwards.