feat(grafana): Use ntfy for alerts instead of matrix-hookshot

configuration/services/metrics/victoriametrics.nix

@@ -89,10 +89,6 @@ in
         "127.0.0.1:8082"
       ];
 
-      # Configured in the hookshot listeners, but it's hard to filter
-      # the correct values out of that config.
-      matrixHookshot.targets = [ "127.0.0.1:9001" ];
-
       victorialogs.targets = [ config.services.victorialogs.bindAddress ];
     };
   };