Group Set Error in Hypothesis Assignments After a Canvas Course Term Has Ended

## Bug report form
### Steps to reproduce
1. In a Canvas course, create a Hypothesis assignment with groups enabled.
2. In the course settings, change the term to a term whose end date is set in the past. This is to simulate as if the course has ended.

3. Using a Canvas instructor account, open the Hypothesis assignment.

### Expected behaviour
The Hypothesis assignment will open successfully.

### Actual behaviour
Tell us what happens instead.
`Group Set Not Found `Error shows up

### Browser/system information
Chrome 149, MAC OS 26.0

### Additional details
If a user with admin role is enrolled in a course as an instructor, that user is able to open the Hypothesis assignment successfully.

Sample assignment: https://hypothesis.instructure.com/courses/742/assignments/9577 (Use instructor account for education+demoinstructor2@hypothes.is)

Log in New Relic: https://onenr.io/0ZQWPA8xpwW

HS Ticket: https://app.hubspot.com/contacts/6291320/record/0-5/45836352788

The error is coming from line 96 of https://github.com/hypothesis/lms/blob/main/lms/product/canvas/_plugin/grouping.py#L96