test: benchmark release network for mana/second

[just-mitch]

After we can run the smoke test on a live, release network, we need to add some benchmarking to measure the network's mana/second.

transfer_in_public is currently 88940 mana. So call it 100 Kmana.

So if we have 9 seconds to build a block, and we need to put 36 transactions in it, and suppose they are all public transfers, that means we need to be at 3.6 Mmana/s.

So call it 4 Mmana/s to be safe.

Thus, our passive gating test should assert this.