Deprecate logging hooks
The registry supports logging hooks, which currently can only be used for email notifications. This functionality is dependent on the logging library support for hooks, which is a bad idea.
I doubt that email notifications remain useful at this point, given that alerts based on log entries are nowadays commonly handled by alerting tools and/or log collectors/indexers. Apart from that, the only possibly useful hooks would be for error reporting, but ideally, that should be handled separately from logging, with an agent, like Sentry.
Considering this, I propose that we deprecate this feature.
Update: This has been confirmed and included in the %13.3 release post (gitlab-com/www-gitlab-com!59716 (merged)). The feature will be removed by January 22nd, 2021.