adwaita-icon-theme updated its cursor metaphors and changed all DnD
cursors to use arrows instead of hands, except for the grab related
ones. Mutter was using "grabbing" as default DnD cursor, which now
does not match the other DnD cursors ("copy" and "no-drop") anymore.
Change this to the "default" cursor.
Additionally, because the "no-drop" cursor now puts a stronger emphasis
on the crossed out symbol also prefer "default" for
META_CURSOR_DND_IN_DRAG and only use "no-drop" for things that
explicitly don't accept a drop.
Related: https://gitlab.gnome.org/GNOME/adwaita-icon-theme/-/merge_requests/63
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3532>
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