Spike to include Gossip module in Otter tests

Experiment to see if it is possible to use the standard Gossip implementation instead of `SimulatedGossip`. The resulting tests will likely not be deterministic, but hopefully, they will be more stable, faster, and easier to work with than JRS tests.

Start by locating the Otter tests and their current SimulatedGossip setup, then compare that path with the standard Gossip implementation and the existing JRS tests. Determine whether the substitution is feasible and document the resulting test stability, speed, and maintainability trade-offs; done means a clear feasibility result.

Written by the indexing model from the issue text.