* Users can only opt-out of external ads
* Move random sampling out of FilteredAdsQuery
* Refactor filtered_ads_query_spec
* Add test for new permit_adjacent setting
* Rubocop
* Use permit_adjacent_sponsors on article sidebar and post-comments
* Remove, unused
* Update copy
* type_matched -> type_of_ads
* Remove non-applicable test
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Co-authored-by: Ridhwana <ridhwana.khan16@gmail.com>
* Make user_id optional for DisplayAdEvent
* Track when DisplayAd is visible to user
* Tidy up a bit
* Deleting a user account should nullify related DisplayAdEvents
* Update tests with new association details
