We want to avoid updating the input region on startup, since it incurs
in roundtrips to the X server, but not workspaces struts, since they
affect the visible clip of wallpapers in the workspace. Since next
commits will make the overview be the after-boot screen, we really
don't want the wallpaper to be clipped wrongly.
Allow updating regions while starting up, but only workspace struts.
Make sure input is not updated by accounting for 'this._startingUp'
on 'wantsInputRegion'.
Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1678>
e3f12e3e23