FIX: do not be more aggressive about cleanup on 'q' that close

We were more aggressively cleaning up the Figure via the 'q' hot key than
via closing via Window Manager UI.

mpl_gui/_promotion.py

@@ -87,13 +87,6 @@ def _destroy(event):
                 mgr._destroy_cid = None
             # close the window
             mgr.destroy()
-            # disconnect the manager from the canvas
-            fig.canvas.manager = None
-            # reset the dpi
-            fig.dpi = getattr(fig, "_original_dpi", fig.dpi)
-            # Go back to "base" canvas
-            # (this sets state on fig in the canvas init)
-            FigureCanvasBase(fig)
 
     manager._destroy_cid = fig.canvas.mpl_connect("key_press_event", _destroy)