Move to the exporterhelper's batching process

[jmacd]

The exporterhelper features a batching function that can nearly replace the concurrent batch processor in this repository. This issue is to track the eventual removal of concurrent batch processor in favor of the built-in exporterhelper batching functionality.

If the user has configured the persistent queue, this batching functionality is already ideal. When the user configures no queue or in-memory queue, we prefer the concurrent batch processor for reasons that will be eliminated, eventually.