Fix T73482: Context Menu on any button is broken

What I removed here used to be needed in an earlier version of the
patch, to avoid use-after-frees. This is not the case anymore, so it
seems we can remove this.

Generally the context region code is very weak and inconsistent. If
things were done properly, the line I added shouldn't cause issues -
it's logically correct.

Also fixes T73475.

source/blender/editors/screen/screen_edit.c

@@ -558,9 +558,6 @@ void ED_region_exit(bContext *C, ARegion *ar)
   WM_msgbus_clear_by_owner(wm->message_bus, ar);
 
   CTX_wm_region_set(C, prevar);
-  if (CTX_wm_menu(C) == ar) {
-    CTX_wm_region_set(C, NULL);
-  }
 }
 
 void ED_area_exit(bContext *C, ScrArea *sa)