Don't display the port number in Grafana dash tooltips

Tryfixes / Refs #114 (closed)

If I understand the behavior of current Prometheus and Grafana correctly, this should remove the port number from the payments server labels in Prometheus TDSB.

Maybe my RE2 foo isn't the strongest, but I have the feeling there's a regex handling issue in the Prometheus relabeling code.

morph/grid/local/grid.nix

@@ -131,7 +131,7 @@ let
   };
 
   # TBD: derive these automatically:
-  paymentExporterTargets = [ "payments" ];
+  paymentExporterTargets = [ "payments.monitoringvpn" ];
   blackboxExporterHttpsTargets = [
     # "https://private.storage/"
     # "https://payments.private.storage/"