Pass Prometheus Registry into Client (#5120)

* Add a few metrics to Client

* Improve PrometheusConfig

* Fix client docs

substrate/bin/node/testing/src/bench.rs

@@ -155,6 +155,7 @@ impl BenchDb {
 			None,
 			None,
 			ExecutionExtensions::new(profile.into_execution_strategies(), None),
+			None,
 		).expect("Should not fail");
 
 		(client, backend)