chore: Groth16 have duplicate errors (`InvalidProof` and `ProofInvalid`)

[LHerskind]

In the Groth16 verifier there is both InvalidProof and ProofInvalid errors but only the ProofInvalid is used.

This can be slightly confusing when reading, so I would suggest removing the unused InvalidProof.

InvalidProof from SP1VerifierGroth16 not used anywhere.

sp1-contracts/contracts/src/v4.0.0-rc.3/SP1VerifierGroth16.sol

Line 18 in 0885c34

error InvalidProof();

ProofInvalid from Groth16Verifier used multiple places.

sp1-contracts/contracts/src/v4.0.0-rc.3/Groth16Verifier.sol

Line 21 in 0885c34

error ProofInvalid();

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On the plonk side things are structured differently and it is used.