Removing flip FTAG taggers from DerivationSkeleton.py
Unlike JetFitterNN, FTAG FlipTaggers are not required to run the PhysicsValidation. Removing them from DAOD_PHYSVAL
@duperrin @thuffman note that this is still enabled in OldFlags2NewFlags.py#L163 which is in principle called when the legacy PHYSVAL Derivation config is run.
FYI @tadej