fixes #23954 - test stubs should return dynflow task
ForemanTask.async_task returns a dynflow task, and tests that stub this should also return the same class of object. ForemanTask::Task doesn't have all the same methods as Task::DynflowTask, e.g. get_humanized.
Related issues
Bug #23954: Tests stub controller to return Foreman::Task instead of a Dynlfow task, causing error
fixes #23954 - test stubs should return dynflow task
ForemanTask.async_task returns a dynflow task, and tests that stub this
should also return the same class of object. ForemanTask::Task doesn't
have all the same methods as Task::DynflowTask, e.g. get_humanized.