relates to GRU-69
Modifies replicasync to handle discovering NATS enabled primary replicas explicitly, and passing that info to the NATS Pubsub.
This PR adds a new deployment value to explicitly represent the host or IP that the replica can be reached on. It isn't wired up to the CLI, but piggybacks on the DERP config for now.
We learn the NATS port directly from NATS at runtime, and propagate it thru replicasync to learn all peers for clustering.
Migrate `wg.Add(1); go func() { defer wg.Done(); ... }()` to
`wg.Go(func() { ... })` in tests.
Where the prior pattern passed the loop variable explicitly via a
closure parameter (`go func(id int) { ... }(i)`), drop the parameter and
reference the loop variable directly. Per-iteration loop variables since
Go 1.22 make this safe.
Closes https://github.com/coder/scaletest/issues/151
Closes GRU-71
Use the existing MsgQueue from the original PGPubsub instead of the 2-channel solution originally built here.
Renames `natsSub` to `groupSub`, since conceptually, a "NATS Subscription" already refers to the underlying subscription on the NATS server.
This PR also simplifies the closing of the PubSub to just close each `localSub`. When the last `localSub` for an event is closed, it unsubscribes and remove the `groupSub`. This ensures we go through the same code paths closing normally and at end of day.
Jon Ayers