remove sleep from CfgTick reader/source

[ameihm0912]

Creating as a draft for now,

This removes the thread sleep from the UnboundedSource advance interface. This seems to not be required, however the behavior of the advance method is dependent on the runner being used. The direct runner will apply an exponential backoff on repeated advance calls that return false. Dataflow seems to handle this differently.

PR'ing as a draft until we can get a bit more information together on the proper way to handle scenarios where the underlying source has no elements to provide.