Mention that `skip_callback` should be avoid in factories in docs

doc/development/testing_guide/best_practices.md

@@ -1205,6 +1205,8 @@ GitLab uses [factory_bot](https://github.com/thoughtbot/factory_bot) as a test f
 - Factories don't have to be limited to `ActiveRecord` objects.
   [See example](https://gitlab.com/gitlab-org/gitlab-foss/commit/0b8cefd3b2385a21cfed779bd659978c0402766d).
 - Factories and their traits should produce valid objects that are [verified by specs](https://gitlab.com/gitlab-org/gitlab/-/blob/master/spec/factories_spec.rb).
+- Avoid the use of [`skip_callback`](https://api.rubyonrails.org/classes/ActiveSupport/Callbacks/ClassMethods.html#method-i-skip_callback) in factories.
+  See [issue #247865](https://gitlab.com/gitlab-org/gitlab/-/issues/247865) for details.
 
 ### Fixtures