For the screensaver service, it is quite normal that a consumer only subscribes to the "ActiveChanged" signal without calling any methods.
The result is that we don't know about the consumer, and shut down the service anyway after we hit the timeout.
If this happens, we break functionality like gnome-settings-daemon's screen blanking on idle.
Fix this by simply disabling auto-shutdown for the service, which also reflects the expectation that the screen saver service is always running in a GNOME session.
Fixes #4114 (closed)