XxTriviumxX and @TRInvictus I ran into the same issue today. It turns out, the options are still there. But finding them is perhaps somewhat counterintuitive. Instead of tapping directly on the (now new) toggle, simply tap to the left of it, i.e., where it says "Allow background usage," or on any other part of that option, other than on the toggle itself. You'll then navigate to a screen where you can select between Optimized and Unrestricted, just as before.
If you wish to set an app to Restricted mode, simply toggle off Allow background usage for the app. This is the same as previous Restrictedoption.