screencopy: Without draw_cursor, omit dnd icon from toplevel capture

It seems https://github.com/pop-os/cosmic-comp/pull/1638 caused an issue
in cosmic-workspaces, where if there are multiple toplevels, when
dragging a toplevel, the drag surface would appear in capture for other
toplevels.

For now, omit drag surface in toplevel capture without `draw_cursor`.
Though I guess ultimately we do want it for metadata cursor capture in
the portal, but not in cosmic-workspaces? Maybe the protocol needs some
additional option for this...

src/wayland/handlers/screencopy/render.rs

@@ -602,6 +602,9 @@ pub fn render_window_to_buffer(
                 );
             }
 
+            // TODO cosmic-workspaces wants to omit, but metadata cursor capture in portal should
+            // still include dnd surface in window capture buffer?
+            if draw_cursor {
                 if let Some(dnd_icon) = get_dnd_icon(&seat) {
                     elements.extend(
                         cursor::draw_dnd_icon(
@@ -615,6 +618,7 @@ pub fn render_window_to_buffer(
                     );
                 }
             }
+        }
 
         elements.extend(AsRenderElements::<R>::render_elements::<
             WindowCaptureElement<R>,