Add raccoon node exporter monitoring

Reviewed-by: Aleix Boné <abonerib@bsc.es>

m/hut/monitoring.nix

@@ -250,6 +250,14 @@
           module = [ "raccoon" ];
         };
       }
+      {
+        job_name = "raccoon";
+        static_configs = [
+          {
+            targets = [ "127.0.0.1:19002" ]; # Node exporter
+          }
+        ];
+      }
       {
         job_name = "ipmi-fox";
         metrics_path = "/ipmi";