Consider reducing the number of iterations for some hint integration benchmarks

[fmoletta]

Some hint integration benchmarks take considerably longer than others, their number of iterations could be reduced to avoid long benchmark times, which becomes an issue once they get added to the CI pipeline. The longest running benchmarks include: (>2s) uint256_integration_benchmark keccak_integration_benchmark (>2.5s) scecp_integration_benchmark blake2s_integration_benchmark (>3.5s) operations_with_data_structures_benchmarks