Excluded services vs PricingService with multiple services

[mkurek]

Assume that PricingService PS_X has Service S_Y in excluded services, and Service S_Y is assigned to PricingService PS_Y, which besides S_Y has also Services S_W, S_Z and S_A.

Services S_W, S_Z and S_A should be charged by PricingService PS_X, but this line:

ralph_pricing/src/ralph_scrooge/models/service.py

Line 270 in c3fc864

ps = ps.exclude(excluded_services__in=self.services.all())

cause that whole PricingService PS_X (and Services S_W, S_Z, S_A which are assigned to it) won't be charged by PricingService PS_X.