* Create Articles::ScoreCalcWorker
* Create Articles::ScoreCalcWorker spec
* Update references to the new ScoreCalcWorker
* Refactoring conditional callbacks and biz logic
- Move update_columns to a model method
- Move conditions on callback to guard clause in callback method
- Make article_destroy_spec more explicit
Related to: #5305
In order to move all the jobs to Sidekiq, this commit creates a new
Articles/BustMultipleCachesWorker using Sidekiq based on the
Articles/BustMultipleCachesJob (this one is not removed until we know
that any job on this one will be performed).
* fixed `ActiveRecord::NotFound` issue for articles, on article destroy
* extracted ActiveJobs from article callbacks
* added specs for article and reaction deletions
