Rather than truncating. This allows us to preserve any existing
configuration (e.g. overlayfs by default).
(cherry picked from commit 954957e6099eac98f99cea2d3434ae3438d6cde1)
Due to #1369794 , anaconda cannot currently manipulate sysv
services in F25+. So to work around this, take 'network' out of
the services lines in all kickstarts and instead manipulate
it in the %post section, with chkconfig.
Also remove rsyslog from the Atomic image services line because
it doesn't appear to be included in the OStree tree at present
and so attempting to enable the service breaks Atomic image
compose, see e.g.:
https://kojipkgs.fedoraproject.org//work/tasks/9022/15349022/oz-x86_64.log
also correct the name of the ssh service in fedora-arm-base.ks;
it's sshd not ssh.
