When an artidoc displays readonly static list fields, it expects decorators associated to the values to use tlp colors.

However, when a decorator uses a legacy color, the app crashes, showing an empty state "This artidoc is empty, or there is nothing you can see".

Even though the old color palette is now deprecated and has disappeared,  we should still make sure that the color is not legacy: they can still exist in old XML templates and old trackers.

They should be detected and ignored.