fix: Prevent the model from fetching if the course_id is missing

[rijuma]

Description:

When the student-proctored-exam-container element is missing, the view tries to fetch a model with undefinedas an id since course_id is not set. This PR checks for its existence before fetching.

JIRA:

COSMO-472🔒

Pre-Merge Checklist:

• Updated the version number in edx_proctoring/__init__.py and package.json if these changes are to be released.
• Described your changes in CHANGELOG.rst
• Confirmed Github reports all automated tests/checks are passing.
• Approved by at least one additional reviewer.

Post-Merge:

• Create a tag matching the new version number.

[rijuma]

Closed. The views for the special exams from this repo are no longer used, so maybe will be removed in a future update.
For now we are going to remove their initialization in edx-platform.