The edge lighting setting didn't disappear! 😉 You can find it here: Settings > Notifications > Set notifications as brief > Brief pop-up settings > Edge lighting style.
But when you go in that menu you are unable to choose a colour for each app. You can choose "color by app", but then you are stuck with the colour that had been defined for that app when the actual, full menu was still there.
Also now there is no option to use edge lighting only when screen is off - the way i liked it.