Theme: adjust active UV face color in the theme

This color had it's alpha reduced in the drawing code,
as the active face is no longer stippled.

Now the color is used from the theme without adjusting the alpha.

release/scripts/presets/interface_theme/blender_light.xml

@@ -724,7 +724,7 @@
         freestyle_face_mark="#7fff7f33"
         face_back="#00000000"
         face_front="#00000000"
-        editmesh_active="#ffffff80"
+        editmesh_active="#ffffff40"
         wire_edit="#c0c0c0"
         edge_select="#ff8500"
         scope_back="#727272ff"