request_func for remove_from_load_balancer (and friends)

- [x] Mangle `supervisor.SupervisorService`
- [x] Mangle `launch_server_v1.delete_server`
- [x] Mangle `launch_server_v1.remove_from_load_balancer`
It calls the method on the next object in the MRO, which might be necessary, since this patch introduces multiple inheritance.