consignment processing: node_ids should not collect genesis ID

[zoedberg]

in #195 a fix has been introduced to avoid processing the genesis ID:

if transition_id.as_inner() == contract_id.as_inner() {
    continue;
}

but as commented by @dr-orlovsky in https://github.com/RGB-WG/rgb-node/pull/195#issuecomment-1242162275 the genesis ID should not even appear in the node_ids list.

So we should verify why that happens, prevent it from happening and then we should be able to remove the aforementioned check