Always generate generics in delegation that match trait in trait impl scenario
After rust-lang/rust#151864 there is a change in delegation code generation in `trait impl` cases: after rust-lang/rust#151864 we started to look at user-specified args and generate functions, whose generics may not match the signature of the function that is defined in trait. Such handling of delegation from trait impl is not correct, as the generated function should always have the same generics as its signature function in trait.
This addresses the "Fix generic params generation in trait impl case" future work from rust-lang/rust#151864
r? @petrochenkov
Jonathan Brouwer
3d486d2ffc