Reported in p1732636371343669-slack-C07418EJ0 and 9083297-zen

Proposed Changes

Remove obsolete workaround code introduced in #2658.

Testing Instructions

1. Sign in as a teacher.
2. Edit/create a new course using the new block editor.
3. Click Submit for Review and confirm.
4. Ensure the course is saved.

Pre-Merge Checklist

• PR title and description contain sufficient detail and accurately describe the changes
• Adheres to coding standards (PHP, JavaScript, CSS, HTML)
• All strings are translatable (without concatenation, handles plurals)
• Follows our naming conventions (P6rkRX-4oA-p2)
• Hooks (p6rkRX-1uS-p2) and functions are documented
• New UIs are responsive and use a mobile-first approach
• Code is tested on the minimum supported PHP and WordPress versions