Update logging level in MyHandler and simplify MyMessage class definition

Author: hsvotwa

samples/logging/custom-factory/Core_9/Sample/MyMessage.cs

@@ -1,6 +1,3 @@
 using NServiceBus;
 
-public class MyMessage :
-    IMessage
-{
-}
+public class MyMessage : IMessage;

samples/logging/extensions-logging/Extensions.Logging_4/Sample/MyHandler.cs

@@ -9,7 +9,7 @@ public class MyHandler :
 
     public Task Handle(MyMessage message, IMessageHandlerContext context)
     {
-        log.Warn("Hello from MyHandler");
+        log.Info("Hello from MyHandler");
         return Task.CompletedTask;
     }
 }