Revert "raise floating windows when focusing (Thanks Marcos)"

This commit breaks floating window keyboard focus order
(t/135-floating-focus.t) when you have > 2 floating windows. Since
keyboard focus is more important than saving one click to raise floating
windows, I revert the commit.

Note that we cannot implement this without keeping a third list (beneath
floating_windows and focus) for the z coordinate of a floating window.
This seems not worth it.

This reverts commit 064be457e5.

src/tree.c

@@ -529,7 +529,6 @@ static bool _tree_next(Con *con, char way, orientation_t orientation, bool wrap)
             if (!next)
                 return false;
 
-            floating_raise_con(next);
             con_focus(con_descend_focused(next));
             return true;
         } else {