rescue: don't pull in sockets

rescue: don't pull in sockets

In rescue mode let's not establish all sockets, so that we don't end up
starting a lot of additional services automatically.

Instead of pulling in basic.target we now only pull in sysinit.target
which pulls in local-fs.target and swap.target. That way rescue mode has
all the really basic setup around, but normal services are not started
and not autostarted either.