With the recent session mode changes, the visibility of settings
items is now only set on sessionMode::updated - while the signal
is emitted when the session mode is initialized, settings items
that are added after that are visible regardless of the allowSettings
setting until the next sessionMode::updated signal is received.
Fix this by explicitly setting the initial visibility of settings
items.
https://bugzilla.gnome.org/show_bug.cgi?id=684473