Remove leading / character from API urls

Author: flobernd

src/Elastic.Clients.Elasticsearch/Client/ElasticsearchClient.cs

@@ -139,7 +139,7 @@ internal TResponse DoRequest<TRequest, TResponse, TRequestParameters>(
 
 		TResponse response;
 
-		using (var activity = _activitySource.StartActivity($"Elasticsearch: {request.HttpMethod} {urlTemplate}", ActivityKind.Client))
+		using (var activity = _activitySource.StartActivity($"Elasticsearch: {request.HttpMethod} /{urlTemplate}", ActivityKind.Client))
 		{
 			activity?.SetTag("db.system", "elasticsearch");
 			activity?.SetCustomProperty("elastic.transport.client", true);