Revisit usage of async code highlighted in recent PR

[TimHess]

Describe the bug

Changes from #982 highlight async code that isn't being awaited (whether or not that is correct needs to be reviewed). These files jumped out at me, but please consider reviewing the PR in case I missed any:

• src/Messaging/src/MessagingBase/Handler/Invocation/AbstractMethodMessageHandler.cs
• src/Messaging/src/RabbitMQ/Core/BatchingRabbitTemplate.cs
• src/Messaging/src/RabbitMQ/Core/RabbitTemplate.cs
• src/Messaging/src/RabbitMQ/Host/RabbitMQHost.cs
• src/Messaging/src/RabbitMQ/Listener/AbstractMessageListenerContainer.cs
• src/Messaging/src/RabbitMQ/Listener/DirectMessageListenerContainer.cs
• src/Messaging/src/RabbitMQ/Listener/RabbitListenerEndpointRegistry.cs
• src/Messaging/test/RabbitMQ.Test/Core/BatchingRabbitTemplateTest.cs
• src/Messaging/test/RabbitMQ.Test/Core/RabbitTemplateIntegrationTest.cs
• src/Messaging/test/RabbitMQ.Test/Listener/ContainerShutDownTest.cs
• src/Messaging/test/RabbitMQ.Test/Listener/ExternalTxManagerTests.cs
• src/Messaging/test/RabbitMQ.Test/Listener/ListenFromAutoDeleteQueueTest.cs
• src/Stream/src/StreamBase/Binder/AbstractMessageChannelBinder.cs
• src/Stream/src/StreamBase/Binder/AbstractPollableMessageSourceBinder.cs
• src/Stream/src/StreamBase/Binding/BindingService.cs
• src/Stream/src/StreamBase/Binding/DynamicDestinationsBindable.cs
• src/Stream/src/StreamBase/StreamHost/StreamHost.cs
• src/Stream/test/Binder.Test/AbstractBinderTests.cs
• src/Stream/test/Binder.Test/PartitionCapableBinderTests.cs
• src/Stream/test/StreamBase.Test/Binder/AbstractMessageChannelBinderTest.cs
• src/Stream/test/StreamBase.Test/Binding/BindingServiceTest.cs

[TimHess]

Is #980 related to any of these?