Do not by default run the node-red service as "privileged" service and "root" user

[janvda]

This node-red service is set as a privileged service and node-red runs as root user.

In most cases this is not really needed. It would be nice and secure to be able to run the node-red service as a non privileged service which is not run as root.

Note also the node-red docker image managed by the node-red community is also not running as privileged service and it executes under the user "node-red".
See https://hub.docker.com/r/nodered/node-red-docker/