Refactors our use of `slogtest` to instantiate a "standard logger" across most of our tests. This standard logger incorporates https://github.com/coder/slog/pull/217 to also ignore database query canceled errors by default, which are a source of low-severity flakes.
Any test that has set non-default `slogtest.Options` is left alone. In particular, `coderdtest` defaults to ignoring all errors. We might consider revisiting that decision now that we have better tools to target the really common flaky Error logs on shutdown.
re: #14715
This PR introduces the Coder service prefix: `fd60:627a:a42b::/48` and refactors our existing code as calling the Tailscale service prefix explicitly (rather than implicitly).
Removes the unused `Addresses` agent option. All clients today assume they can compute the Agent's IP address based on its UUID, so an agent started with a custom address would break things.
- `DERPForceWebSockets`: Test that DERP over WebSocket (as well as DERPForceWebSockets works). This does not test the actual DERP failure detection code and automatic fallback.
- `DERPFallbackWebSockets`: Test that falling back to DERP over WebSocket works.
Also:
- Rearranges some test code and refactors `TestTopology.StartServer` to be `TestTopology.ServerOptions` and take a struct instead of a function
Closes#13045
Spike Curtis