Dashbaord::Manager has always been excluded from autoloading as it kept a list of known widgets in a class variable. In #10927, it was moved to app/registries/ to preserve this status and keep it from being autoloaded.

It is possible to rewrite this class in an autoload-friendly manner, where the list of builtin widgets is hardcoded inside the class and then the total list of default widgets is retrieved from Foreman::Plugin when required, instead of plugins appending to the dashboard class variable.

This would:

1. Allow the source file to be kept in app/services/, easier for people to find
2. Allow the class to be reloaded in development, so changes to builtin widgets are immediately visible
3. Allow initialisation to be removed from config/initializers/, speeding up the application load time
4. Make the class more testable, by removing modifications to class variables