NLU Data: add placeholders to nlu data

[threxx (Theresa Z)]

@JulianGerhard Actually, I have an open question right now. It’s because I updated to a higher Rasa Core and NLU Version and there is a lot of debugging. Maybe you could help me out here as well: RasaNLUHttpInterpreter: takes from 1 to 4 positional arguments but 5 were given