* Fixing weighted query hotness grab logic
Prior to this commit, I carried over (albeit imprecisely) logic from the
LargeForemExperimental. That logic was to help limit articles to those
that were published since the user's latest page view.
However, I introduced a bug in this transcription. Now both
LargeForemExperimental and WeightedQueryStrategy use the same logic to
determine the oldest publication date to search for in the feed.
This resolves a bug reported where users were not seeing a large number
of items in their feed.
Incidentally, if a forem has little activity in the 18 hours, there
might be very few items in the feed.
I believe, going forward, we may need to better parameterize how many
hours is considered "stale since last page view".
Related to #15240
* Fixing implementation detail
* Extracting helper method
Prior to this commit, I had introduced a method an put it in a less
ideal module space. This commit extracts that method to a more readily
shareable module space.
I've added a few more specs to help clarify and verify behavior.
* Updating documentation
* Renaming and documenting variables/constants
* Fixing that which I broke
60dc2cc12e