It turns out since `unified` is being used in a lot of places (to mean both *prod* and *pre-prod*), having a `unified-prod` didn't do much help. What we needed was just a `unified-preprod` which I made use of in `rxApp`.

Based on this, we can either leave `unified-prod` in there for someone to use later (it will always have to come before the `unified` definition), or delete it and re-add it as needed later. It uses a positive lookahead now (you were correct that the previous regex was not going to work). There is no test case for it because that condition is unreachable at the moment.

Added test cases for `unified` and `unified-preprod` which are being used at the moment.