Remove CI/CD models directory from `eager_load_paths`

CI/CD models are already located inside `CI` module, thus usual Rails
autoloading principles apply.

See https://github.com/rails/rails/issues/28854 for more details.

config/application.rb

@@ -22,7 +22,6 @@ module Gitlab
     # This is a nice reference article on autoloading/eager loading:
     # http://blog.arkency.com/2014/11/dont-forget-about-eager-load-when-extending-autoload
     config.eager_load_paths.push(*%W(#{config.root}/lib
-                                     #{config.root}/app/models/ci
                                      #{config.root}/app/models/hooks
                                      #{config.root}/app/models/members
                                      #{config.root}/app/models/project_services