Have throttled worker always wait throttleDelay between work calls

[lramos15]

Consider the following case, maxWorkChunkSize of 1 and a throttleDelay of 1000ms. The maxBufferedWork doesn't matter here.

1. Queue a unit at 0ms. It immediately executes as there is nothing in the throttler
2. Queue a unit at 500ms. It immediately executes again as there is nothing in the throttler.

This seems wrong as I don't want my work items to execute without a minimum 1000ms gap in between them. Instead even if the queue is empty, the throttled worker should ensure that the second queue task must wait 500ms before executing so it's been 1000ms since the last unit of work.

This does modify the text behavior slightly, so I am happy to make this an option on the worker options or something, but I was surprised when the worker did not work out of the box like this