As you now say it's just to wash and not prepare it for painting I think maybe just a household cleaner like Flash. Sugar soap may be ok but it could take the shine off the paint. Try it on a small piece first and use a very weak solution.
I think I will stick to the Flash as there is little shine on the doors - maybe some time this year get into some decorating which I loathe getting done.
Can I just say I just loved Flash powder loved it - it has all been watered now so to me there is no substance.