First part of if condition redundant

[EDGDrummond]

https://github.com/docknetwork/crypto/blob/2eee4a6a6cba58c92e18ad5557d6b1a7a4730cfe/compressed_sigma/src/amortized_homomorphism.rs#L79

We check if witnesses.len() > j, but j < witnesses.len() by definition so this is trivially true.