Revert place bubble repositioning changes

In !152 (merged) and !155 (merged) changes where made to try to manually reposition the direction of the place bubble popovers to better avoid covering the headerbar (and search entry).

Unfortunatly in some circumstances it makes the "beak" point in the wrong direction, which looks bad. This is probably due to the fact that we place the popover relative to a rectangle, as the marker is not a GTK widget, but a Clutter actor.

And the logic that was added is a bit complicated. So we're probably better off with the previous behavior for now. And maybe it would be easier to get this right after switching to GTK 4, when markers will be GTK widgets.