Fix issue with adding staff/volunteers under their correct quota tags

Sessions: Saturday 9:00 1 'Instructor', and 1 'Staff on Duty' selected - added Stejara as Instructor - when adding Kiz as staff on duty, it's added under 'Instructor' - removed both names from Instructor, and started with 'Staff on Duty' first....still added under Instructor https://24trots.com/sessions/ses_LjEmVo397ssK

Sessions: Saturday 9:00 1 'Instructor', and 1 'Staff on Duty' selected - added Stejara as Instructor - when adding Kiz as staff on duty, it's added under 'Instructor' - removed both names from Instructor, and started with 'Staff on Duty' first....still added under Instructor https://24trots.com/sessions/ses_LjEmVo397ssK