user/*: don't add -k /etc/skel for system users

user/apache-httpd/apache-httpd.pre-install

user/bind/bind.pre-install

user/chrony/chrony.pre-install

user/dbus/dbus.pre-install

user/distcc/distcc.pre-install

user/nextcloud/nextcloud.pre-install

user/openldap/openldap.pre-install

user/openvpn/openvpn.pre-install

user/pcsc-lite/pcsc-lite.pre-install

user/prosody/prosody.pre-install

user/pulseaudio/pulseaudio.pre-install

user/redis/redis.pre-install

user/rpcbind/rpcbind.pre-install

user/sane/saned.pre-install

user/strongswan/strongswan.pre-install

user/vde2/vde2.pre-install

user/vlc/vlc-daemon.pre-install