IPA verifier initializes a new transcript instead of continuing the Zeromorph transcript

[jtcoolen]

In the decider circuit, during the final Zeromorph opening, the IPA opening subroutine does not reuse the existing transcript (off-circuit prover: https://github.com/EYBlockchain/nightfish_CE/blob/master/plonk/src/nightfall/mle/zeromorph/zeromorph_protocol.rs#L353, in-circuit verifier: https://github.com/EYBlockchain/nightfish_CE/blob/master/plonk/src/nightfall/circuit/verify_zeromorph.rs#L215).