feat: More heracles network dashboard config

nix/base-system/darwin-configuration.nix

@@ -145,6 +145,16 @@
                                 yaxis = "y1";
                             };
                         }
+                        {
+                            source = "http://${config.services.prometheus.listen}";
+                            query = ''
+                                delta(ping_counter{result="dropped"}[5m])
+                            '';
+                            config = {
+                                name_format = "`icmp \${labels.domain} drop count`";
+                                yaxis = "y1";
+                            };
+                        }
                     ];
                 }
                 {