Do not include the fixed and instance column evaluations into the proof

[ConstanceBeguier]

It seems that fixed and instance column evaluations are included into the proof.

See halo2 book section 4.3.1:

See halo2/halo2_proofs/src/plonk/prover.rs:

I think it is not necessary because they are evaluated from public values.
By removing them, we could reduce the size of the proof.