Docker image for sentinel runs the process as root

While testing the latest Docker images for sentinel for Horizon 25.0.0, I found that even if the infrastructure is present to use the sentinel user (i.e. the user exists and it is configured in /etc/passwd with UID 997), the process runs as root.

Also, it would be useful and more professional to copy the /etc/skel/ files to /opt/sentinel to have a better prompt when accessing the container.