Debug discovery of participating agents in Unyt zero arc scenario #612

The zero arc scenario is still not working in the sense that zero arc agents are not found as participating agents. Debugging and fixing this is deferred for now and should be done in isolation in sweettest first.

Originally posted by @jost-s in #597

Suspect that it's rather to do with zero arc than with the Unyt happ. A simplified Wind Tunnel scenario can be used as the template for a sweettest:

• 1 progenitor node to initiate the network
• 1 full arc spend node
• 1 zero arc spend node

The zero arc node should be able to make commitments to the full arc spend node, but no commitments are happening because as the full arc node doesn't see the zero arc node's flag code template, and the zero arc node doesn't see the full arc's template either. The logs are full of AwaitingDeps warnings, supposedly deps from the zero arc, because the full arc nodes should be gossiping and do declare full storage arcs and should be serving missing deps.

AC:

• Debug why the missing deps cannot be retrieved and which node is missing them, possibly also where in the bootstrap process of the scenario it gets stuck.
• The zero arc and full arc spend nodes must be sending commitments to each other successfully.