GObject signals pass the emitting GObject as the first argument to
signal handler callbacks. When refactoring the grab-op-begin/end signals
to remove MetaScreen with commit 1d5e37050df2b8e1db8b5ea301ee0162d77d4b74,
the "screen" argument was replaced with a "display" argument instead of
being removed completely. This made us call the signal handlers with two
identical MetaDisplay arguments, which is very confusing and actually
wasn't handled in a grab-op-begin handler in gnome-shell.
So fix this by not adding the MetaDisplay as an argument to those
signals, GObject will take care of that for us.
Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1734>
9512d58c28