[Comb] Redundant concat op verifier

[maerhart]

The comb.concat operation implements the InferTypeOpInterface which specifies a verifier based on the inferReturnType method. However, we also have a custom verifier that checks the same thing. We should remove the custom verifier for performance reasons.

Thanks @Hatsunespica for making us aware of this in llvm/llvm-project#131480 (comment)