Since Rails 5.2, the behavior of `attribute_changed?` inside `after_save` callbacks has changed, so we need to use `saved_change_to_attribute` instead. The site setting local_process_provider in test mode was covering up the issue.
If you turn it on now, default all users to approved since they were
previously. Also support approving a user that doesn't have a reviewable
record (it will be created first.)
This also includes a refactor to move class method calls to
`DiscourseEvent` into an initializer. Otherwise the load order of
classes makes a difference in the test environment and some settings
might be triggered and others not, randomly.