perf: remove opcode field from witness (-4 bytes per cycle for GPU wi… #705

Job	Run time
cargo fmt	30s
build_cli_no_verifiers_512	9m 0s
ISA tests for simulator	1m 1s
full_recursion_fast	2h 4m 19s
risc_v_tests_delegations	55s
circuits_generated	3m 37s
build_cli_no_verifiers	11m 1s
build_verifier	47s
tests	1m 26s
build_cli_with_verify	1m 15s
verification_example	-1s
large_example	-1s
basic_example	-1s
delegation_example	-1s
oh_bender_incremental_proofs	0s
full_recursion	0s
	2h 33m 47s

Provide feedback