COG Randomized Study of Vincristine; Dactinomycin and Cyclophosphamide (VAC) versus VAC Alternating with Vincristine and Irinotecan (VI) for Patients with Intermediate-Risk Rhabdomyosarcoma (RMS): A Groupwide Phase III Study Pediatric CIRB Closed to Accrual. Pts Have Completed Intervention Completed