glue: otel scrape targets for authelia, grafana and nats move out of the services

Part of #3742.

nix/host-modules/swarm-nats.nix

@@ -459,33 +459,6 @@ in
       }
     ];
 
-    # Declared here rather than in the collector's module: an entry then
-    # exists only where the service that named it runs. Gated on a
-    # collector, because a target nobody reads asserts a collection that is
-    # not happening.
-    #
-    # ⚠️ KNOWN LIMITATION, and it is SILENT. That rule constrains the
-    # target, not the scraper — nothing places the collector on this host.
-    # `swarm-required-services.nix` derives `nats.enable` and `otel.enable`
-    # from one `lib.mkDefault`, so they are co-located by *default*, and an
-    # operator may split them. Split, NATS is never scraped: this host
-    # declares an entry no local collector reads, the collector's host never
-    # enabled this module. No error, no warning — a healthy exporter and an
-    # empty dashboard.
-    #
-    # Not guardable: separate hosts are separate evaluations with no shared
-    # context, so this one cannot see what that one runs. Saying so is the
-    # only mechanism there is.
-    #
-    # ⚠️ `swarm.otel`, not `hyperhive.otel` — two collectors one word apart,
-    # and only this one reads `scrapeTargets`. Written in full so the gate
-    # and the option it gates are visibly the same path.
-    services.hyperhive.swarm.otel.scrapeTargets =
-      lib.mkIf config.services.hyperhive.deploy.swarm-otel.enable
-        {
-          nats = "127.0.0.1:${toString cfg.metricsPort}";
-        };
-
     # Open the client port on the bridge, so agent containers can reach
     # the queue. `privateNetwork = false` below means the server binds in
     # the host netns, which is the precondition this option names — but