fix generating multiple upstreams of same type

lib.nix

@@ -28,8 +28,7 @@ rec {
 
       # Subindex by resource names, listener types, and convert to upstreams
       (lib.mapAttrs (_: workers: lib.pipe workers [
-        (lib.concatMap (worker: worker.settings.worker_listeners))
-        lib.lists.head # only select one listener for the worker to avoid cache thrashing
+        (lib.concatMap (worker: [ (lib.lists.head  worker.settings.worker_listeners) ]))
         lib.flatten
         mapListenersToUpstreamsByType
       ]))