Do not modify main /etc/NetworkManager/NetworkManager.conf as it would
cause conflicts during updates. Use
/etc/NetworkManager/conf.d/30-qubes.conf instead.
Also remove some dead code for dynamically generated parts (no longer
required to "blacklist" eth0 in VMs - we have proper connection
generated for it). It was commented out for some time already
FixesQubesOS/qubes-issues#1176