WARNING CS0105 (#6645)

* [WARNING CS0105] Remove `The using directive for 'System.Threading' appeared previously in this  namespace`

* Adding more `WARNING` to `CS0105`

Author: eaba

src/contrib/cluster/Akka.Cluster.Metrics.Tests.MultiNode/ClusterMetricsExtensionSpec.cs

@@ -14,7 +14,6 @@
 using Akka.Configuration;
 using Akka.Remote.TestKit;
 using FluentAssertions;
-using Akka.Configuration;
 using Akka.MultiNode.TestAdapter;
 using FluentAssertions.Extensions;
 using ConfigurationFactory = Akka.Configuration.ConfigurationFactory;

src/contrib/cluster/Akka.Cluster.Metrics.Tests.MultiNode/ClustetMetricsRoutingSpec.cs

@@ -21,7 +21,6 @@
 using Akka.Remote.TestKit;
 using Akka.Routing;
 using FluentAssertions;
-using Akka.Configuration;
 using Akka.MultiNode.TestAdapter;
 using FluentAssertions.Extensions;
 using Address = Akka.Actor.Address;

src/contrib/cluster/Akka.Cluster.Metrics.Tests.MultiNode/Sample/StatsSampleSpec.cs

@@ -13,7 +13,6 @@
 using Akka.Configuration;
 using Akka.Remote.TestKit;
 using FluentAssertions;
-using Akka.Configuration;
 using Akka.MultiNode.TestAdapter;
 using FluentAssertions.Extensions;
 using ConfigurationFactory = Akka.Configuration.ConfigurationFactory;

src/contrib/cluster/Akka.Cluster.Metrics.Tests/ClusterMetricsSettingsSpec.cs

@@ -15,7 +15,6 @@
 using Xunit;
 using FluentAssertions;
 using FsCheck;
-using Akka.Configuration;
 using FluentAssertions.Extensions;
 using ConfigurationFactory = Akka.Configuration.ConfigurationFactory;
 

src/contrib/cluster/Akka.Cluster.Metrics.Tests/WeightedRouteesSpec.cs

@@ -16,7 +16,6 @@
 using Akka.TestKit;
 using Akka.Util.Internal;
 using FluentAssertions;
-using Akka.Configuration;
 using Xunit;
 using ConfigurationFactory = Akka.Configuration.ConfigurationFactory;
 

src/contrib/cluster/Akka.Cluster.Metrics/Routing/ClusterMetricsRouting.cs

@@ -18,7 +18,6 @@
 using Akka.Routing;
 using Akka.Util;
 using Akka.Util.Extensions;
-using Akka.Configuration;
 
 namespace Akka.Cluster.Metrics
 {

src/contrib/cluster/Akka.Cluster.Metrics/Routing/MetricSelectors.cs

@@ -12,7 +12,6 @@
 using Akka.Cluster.Metrics.Serialization;
 using Akka.Configuration;
 using Akka.Util;
-using Akka.Configuration;
 
 namespace Akka.Cluster.Metrics
 {

src/contrib/cluster/Akka.Cluster.Sharding.Tests.MultiNode/ClusterShardingRegistrationCoordinatedShutdownSpec.cs

@@ -12,8 +12,6 @@
 using Akka.Actor;
 using Akka.Remote.TestKit;
 using FluentAssertions;
-using System.Threading.Tasks;
-using System.Threading;
 using Akka.Event;
 using Akka.MultiNode.TestAdapter;