Prior to this commit, we had a couple of references to magic strings
regarding DisplayAdEvent objects. This commit seeks to consolidate that
behavior.
In a handful of cases we had javascript variables, but as these JS files
are `erb` templates, we can inject the constant as well. This reduces
repetition of knowledge.
* Favoring delete_all on user relationships
Prior to this commit, several of the user's "has_many" were marked as
`depenedent: :destroy`.
In the case of :destroy, ActiveRecord instantiates each object and then
runs destroy. Whereas in the case of :delete, ActiveRecord issues a SQL
command to delete the related files.
It is often "safer" to use :destroy, as it guarantees that you'll
instantiate the record and run it's callbacks. But sometimes you have
to go with the speed of SQL.
And while not directly related to #15424 it is representative of our
callback ecosystem creating some unexpected computational loads.
Related to #15442 and #15424
* Noting models that user no longer cascade destroys
