[swaps] Fix `swap_exact_amount_*` benchmarks for Rikiddo

[maltekliemann]

We need to replace

#[pallet::weight(T::WeightInfo::swap_exact_amount_in_cpmm())]

with

#[pallet::weight(T::WeightInfo::swap_exact_amount_in_cpmm().max(T::WeightInfo::swap_exact_amount_in_rikiddo(T::MaxAssets::get())))]