Issue [#3520459]: Fix missing schedule data in instructor popup

Problem:

When clicking on an instructor’s name in the schedule, the popup appears with the instructor’s name, but no class data is displayed. This is due to a mismatch between the data variable used in the JS logic and the template.

Before:

After:

This MR removes the redundant instructorPopup_schedule property and instead stores schedule data directly inside instructorPopup.schedule.

What changed:

• Removed instructorPopup_schedule from data
• Refactored populatePopupInstructor() to assign filtered data to instructorPopup.schedule
• Removed unnecessary watchers on instructorPopup_schedule