Remove AWSCredentials registration since its disposal by the framework breaks FallbackCredentialsFactory's assumptions

RefreshingAWSCredentials will throw an exception if it's been disposed of (and used via FallbackCredentialsFactory)

Author: chase-miller

extensions/src/AWSSDK.Extensions.NETCore.Setup/ServiceCollectionExtensions.cs

@@ -248,8 +248,6 @@ private static IServiceCollection AddCredentialsFactoryInternal(
                 collection.Add(serviceDescriptor);
             }
 
-            collection.TryAddTransient<AWSCredentials>(sp => sp.GetRequiredService<IAWSCredentialsFactory>().Create());
-
             return collection;
         }