Added FOCUS-47628 - Third Party Systems: Better Handling of Schedule Term Overrides in API - OneRoster /enrollments

This update improves Third Party Systems by correcting how enrollment end dates are handled for students with a Semester 1 override on a full-year course. Previously, the enrollment end date reflected the course end date instead of the Semester 1 end date. This update adjusts the GET /enrollments logic to reference the schedule.marking_period_id, if set, to accurately determine the schedule's end_date when no explicit value is provided. This ensures more accurate reporting of enrollment periods.