This setting was enabled to make the KCM defaults slightly more consistent, as
the partial settings `AutomountOnLogin` and `AutomountOnAttached` are enabled by
default and the KCM enables the general `AutomountEnabled` settings from those.
But this seems to be problematic for some use cases (reported on fresh-installed
systems like Fedora), so we need to disable it by default.
As the KCM compose the general option from the two partial ones, we need to disable
them too, so they're in sync and the Default state is stable.
This reverts commit 2cb4ef4d73.
This change is not needed due to the new UX in the Disks & Devices
applet, which addressed the primary complaint about automount in
different way. Going back to the prior behavior also addresses several
other concerns about the new default from security and multi-user
perspectives.
