Fix duplicate preference key shortcut on macOS, causing test failure

After recent changes in 86f659a.

scripts/presets/keyconfig/keymap_data/blender_default.py

@@ -827,8 +827,6 @@ def km_screen(params):
             ("screen.screen_full_area", {"type": 'SPACE', "value": 'PRESS', "ctrl": True, "alt": True},
              {"properties": [("use_hide_panels", True)]}),
             ("screen.redo_last", {"type": 'F9', "value": 'PRESS'}, None),
-            # Preferences
-            ("screen.userpref_show", {"type": 'COMMA', "value": 'PRESS', "ctrl": True}, None),
         ])
     else:
         # Old keymap
@@ -848,14 +846,21 @@ def km_screen(params):
             ("screen.region_flip", {"type": 'F5', "value": 'PRESS'}, None),
             ("screen.redo_last", {"type": 'F6', "value": 'PRESS'}, None),
             ("script.reload", {"type": 'F8', "value": 'PRESS'}, None),
-            ("screen.userpref_show", {"type": 'U', "value": 'PRESS', "ctrl": True, "alt": True}, None),
         ])
 
+    # Preferences
     if params.apple:
-        # Apple undo and user-preferences.
         items.extend([
             ("screen.userpref_show", {"type": 'COMMA', "value": 'PRESS', "oskey": True}, None),
         ])
+    elif not params.legacy:
+        items.extend([
+            ("screen.userpref_show", {"type": 'COMMA', "value": 'PRESS', "ctrl": True}, None),
+        ])
+    else:
+        items.extend([
+            ("screen.userpref_show", {"type": 'U', "value": 'PRESS', "ctrl": True, "alt": True}, None),
+        ])
 
     return keymap