NetworkManager (etcnet) is default now.

NM_CONTROLLED should always be set together with DISABLED;
otherwise, it's possible to reach the state where
DISABLED=no but NM_CONTROLLED=yes, and have the interface
controlled by both NM and etcnet.

When renaming HOSTNAME in the alterator, switches managing interface to etcnet.
This creates problems for users.
This partial reverts commit d4170557.

This reverts commit 226a2395.

Users are getting upset about NetworkManager being unable to
configure "System EthX" connections that are meant to set up
with "acc" (which isn't obvious at all).

See-also: https://forum.altlinux.org/index.php?topic=42519.0

This needs further refinement regarding p7/t7 specifically:
NM behaviour regarding defaults differs in sisyphus and this
has led to livecds booting with DHCP networking but installed
systems booting without configured interfaces.