* Use normal db transactions around tests
An unrelated spec failure was observed when this was run before
another test expecting the seed data to be present. It looks like the
specific pain point in https://github.com/forem/forem/pull/8865 was
around an rss reader spec (which is no longer in use) and I'd like to
try reverting this truncation behavior here.
The minimal failing test case I had on master was this
```
rspec ./spec/system/dashboards/user_sorts_dashboard_articles_spec.rb:44 ./spec/lib/data_update_scripts/fix_profile_field_edge_cases_spec.rb
```
The find_by(attribute:...) in the edge case spec returned nil (since
there was no such profile field, the table had been truncated). Tests
pass locally so this might be fine to just leave on the defaults (if
that's the case the truncation support added in #8865 can also be
removed, this is the last caller).
* Reenable transactional feeds imports
rhymes pointed out that a second test uses this db_strategy and that's
the successor to the rss_feed_spec.rb that was the initial issue.
Attempt removal of the truncation strategy, and reenable the
transactional tests, for the feeds import.
* Remove database cleaner
Having removed the last use of it (in the feeds import spec) we no
longer need this gem.
* remove spec support for database cleaner
* Add earlier_than to Feeds::Import
* Ignore feeds that have been imported in the last 4 hours
* Make earlier_than mandatory in Feeds::ImportArticlesWorker
* Add explanatory comment to how RssReaderFetchUserWorker works
* Add Feeds::ImportWorker worker
* Enable Feeds::Import for single user feed fetching behind a feature flag
* Add Feeds::ValidateUrl service
* Add feature flag to user's validate feed URL feature
* Remove todo notices
* Add feature flag to fetch_all_rss task
* Add feature flag to RssReaderWorker
* Bring back short-circuit for Articles::RssReaderWorker
* Add the parallel gem
* Add prototype version of Feeds::Import with parallel URL fetching and parsing
* Tune Feeds::Import and add rake task for local tests
* Add rough measurer tool
* Add specs
* Apply suggestions by @citizen428
* Replace silence with silent
* No need for eager loading
* Add temporary Articles::DevFeedsImportWorker
* Remove temporary rake task
* Add basic error handling, copied from RssReader
* Fix error handling
* Remove temporary measuring rake task
* Remove logging added for development purposes
* Add info and error logging on error level
