Don't prompt to start avahi
In some use cases, avahi-daemon is causing issues and is disabled with:
systemctl mask avahi-daemon.socket avahi-daemon.service
systemctl stop avahi-daemon.socket avahi-daemon.service
In that scenario, simple-scan is showing a confusing prompt while scanning for devices:
Authentication is required to manage system services or other units.
An application is attempting to perform an action that requires privileges.
Authentication as the super user is required to perform this action.
Password for administrator:Details
polkit.subject-pid: 4001
polkit.caller-pid: 4001
Action: org.freedesktop.systemd1.manage-units
Vendor: The systemd ProjectCancel Authenticate
By pressing the Cancel button, the user can properly use the application and scan using the list of scanners defined by the sysadmin.
This wasn't an issue in the past (e.g. 3.36), it started with some newer simple-scan version (currently using 42.0).
Please provide a way to avoid displaying that confusing dialog.