Use priority queue by number of url finds

## The problem

Reported in Crawlee: Use priority queue by number of url finds.

## The fix

Wontfix, by design. Crawlee will not get a priority queue that orders URLs by how many other pages link to them: it would have to be implemented across the Apify platform and API, not just in Crawlee, and URL frequency is not stored anywhere (crawlee cannot know a site's link structure upfront). If you need rough prioritization, see the workaround discussed in apify/crawlee#1309.