* Use the tag_list method, rather than the cached_tag_list attribute
This is a follow on to #15456 and #15637
Saving the article in #15637 was a work-around to force the article to
have a valid cached tag list. However, we can rely on the tag_list
method to find the associated tags.
Update the worker to use tag_list (rather than the decorator's
cached_tag_list.array) and flatten the tag list rather than flat
mapping String#split over the non-nil cached_tag_lists.
* Remove unused join on tags
The query logging showed each article's tags were loaded twice in a
row (select by id, immediately followed by select by id). Removing the
join removed this behavior. I suspect mapping `#tag_list` over
articles is ignoring the loaded tags.
Performance (in my local environment) improved about 30% when this join was removed.
* Separate followed and "anti-followed" tags
* Minor code change
* Indicate "anti-followed" tags in sidebar
* Fix UpdatePointsWorker spec
* Cries in Arel
* Use antifollow scope more selectively
* Add spec for not_cached_tagged_with_any scope
* Add explanatory comment
* Remove unused route
* Update comment
* Remove unrelated change, figure out why > 1 later
* Need more ☕
* Avoid false positives in spec
* Change handling of ingored tags in sidebar
* Add explanatory comment
