Possible missing constraint in biggroup `compute_wanf`?

Somebody left a `TODO` here: https://github.com/AztecProtocol/aztec-packages/blob/5cde0a11e77de304842090d33d728af9e2a085f2/barretenberg/cpp/src/barretenberg/stdlib/primitives/biggroup/biggroup_nafs.hpp#L407
We should remember to follow up on this