fix(risc_v_simulator): replace println with log #823

Job	Run time
full_recursion_fast	1m 49s
build_cli_with_verify	1m 12s
tests	1m 14s
ISA tests for simulator	55s
cargo fmt	26s
build_cli_no_verifiers	2m 42s
build_cli_no_verifiers_512	2m 0s
risc_v_tests_delegations	42s
circuits_generated	2m 9s
build_verifier	3m 1s
basic_example	2m 43s
delegation_example	5m 10s
large_example	4m 37s
oh_bender_incremental_proofs	1m 34s
verification_example	7m 22s
full_recursion	3m 34s
	41m 10s

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