Remove threaded.js and references to maxThreads

[alanbixby]

Discovered during #703 review; maxThreads is only referenced in threaded.js which in turn has no utilization in the library whilst being a util function.

threaded.js appears to be a helper function for fetching multiple pages at once; a decent idea but limited use case since most of the multipage endpoints we care about are cursor based and have to be made sequentially

Be mindful to remove the references in settings.json and the associated typings/JSDocs