Currently when the foreground service conversation stops we increase the
verification failed count and try to start it again, while if a
background service has been stopped we just ignore it.
This is causing a various number of issues, for example in the case of
the fingerprint authentication service, it is normally configured to die
after a timeout, and we end up never restarting it (while the UI still
keeps showing to the user the message about swipe/touch the device).
So, in such case let's just consider it a "soft" verification failure
that doesn't increase the failures count but will cause us to reset the
UI and try to restart the authentication (and so the affected service).
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1652>