edge lighting is part of good lock which I don't think is available during the beta, on full roll out this should be updated and available. however I could be wrong, but I hope Samsung don't remove this feature I really like it.
As @charlas has already mentioned, it is still possible to access the Edge Lighting setting during our Beta Program 😉. The name of the setting has been slightly changed, but it's still there. Thanks @charlas for sharing your knowledge with other users! 😀