UV/Image: Remove Legacy Drawing

With D8234 a new drawing method for UV/Image editor was introduced. For debugging
reasons we left the old drawing method in the code base. This patch will remove
the old drawing method.

Reviewed By: Clément Foucault

Differential Revision: https://developer.blender.org/D9011

release/scripts/startup/bl_ui/space_userpref.py

@@ -2218,7 +2218,6 @@ class USERPREF_PT_experimental_debugging(ExperimentalPanel, Panel):
             context, (
                 ({"property": "use_undo_legacy"}, "T60695"),
                 ({"property": "use_cycles_debug"}, None),
-                ({"property": "use_image_editor_legacy_drawing"}, "T67530"),
             ),
         )