Make localhost the default for Grafana's TSDBs

Fewer lines almost always better.  Also, we don't want to spread
these out unless we have to.

morph/lib/monitoring.nix

@@ -28,9 +28,4 @@ rec {
     # Loki 0.3.0 from Nixpkgs 19.09 is too old and does not work:
     # ../../nixos/modules/monitoring/server/loki.nix
   ];
-
-  services.private-storage.monitoring.grafana = {
-    prometheusUrl = "http://localhost:9090/";
-    lokiUrl = "http://localhost:3100/";
-  };
 }

nixos/modules/monitoring/server/grafana.nix

@@ -18,13 +18,13 @@ in {
     prometheusUrl = lib.mkOption
     { type = lib.types.str;
       example = lib.literalExample "http://prometheus:9090/";
-      default = "http://prometheus:9090/";
+      default = "http://localhost:9090/";
       description = "The URL of the Prometheus host to access";
     };
     lokiUrl = lib.mkOption
     { type = lib.types.str;
       example = lib.literalExample "http://loki:3100/";
-      default = "http://loki:3100/";
+      default = "http://localhost:3100/";
       description = "The URL of the Loki host to access";
     };
   };