Use hut-substituter module in owl{1,2} and raccoon

m/module/hut-substituter.nix

@@ -1,9 +1,10 @@
 { config, ... }:
-  # Don't add hut as a cache to itself
-  assert config.networking.hostName  != "hut";
 {
-  nix.settings = {
-    substituters = [ "https://jungle.bsc.es/cache" ];
-    trusted-public-keys = [ "jungle.bsc.es:pEc7MlAT0HEwLQYPtpkPLwRsGf80ZI26aj29zMw/HH0=" ];
-  };
+  nix.settings =
+    # Don't add hut as a cache to itself
+    assert config.networking.hostName != "hut";
+    {
+      substituters = [ "https://jungle.bsc.es/cache" ];
+      trusted-public-keys = [ "jungle.bsc.es:pEc7MlAT0HEwLQYPtpkPLwRsGf80ZI26aj29zMw/HH0=" ];
+    };
 }