Now that the app menu indicator is no longer shown, it shouldn't be possible
to toggle the popup menu via keyboard shortcut anymore, so remove the code
and gsettings definitions for that.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2610>
intltool is unmaintained nowadays while upstream gettext gained
support for formats like GSettings schemas and .desktop files,
and offers a mechanism to teach it about other XML formats not
yet supported out of the box which we can use for the rest.
So there's nothing stopping us, just make the switch ...
https://bugzilla.gnome.org/show_bug.cgi?id=769074