autorunManager: Use a regular urgent notification

autorunManager: Use a regular urgent notification

According to the design, hotplug notifications should no longer offer
an eject action and use regular notification buttons (but using icon
and text), the default action when clicking the notification itself
is to launch the file browser.
Also as the corresponding resident notification is gone, it no
longer makes sense to make the notification transient.

https://bugzilla.gnome.org/show_bug.cgi?id=744815