wayland: Use scale from core wl_output protocol

The “xdg-output” protocol provides clients with the outputs size and position in compositor coordinates, and does not provide the output scale which is already provided by the core “wl_output” protocol.

So when receiving the wl_output scale event, we should update the scale regardless of “xdg-output” support, otherwise the scale will remain to its default value of 1 and the surface will be scaled up by the compositor to match the actual output scale, which causes blurry fonts and widgets.