[#13304] Refactoring for Unit Test Access Controls

[marifer-perezh]

Fixes # 12048

Outline of Solution

Refine access control coverage for update feedback actions
Part of Refactoring for Unit Test Access Controls #13304

Summary

• ensure UpdateFeedbackSessionAction rejects missing sessions and limits updates to instructors with the modify-session privilege

Testing

• ./gradlew test --tests teammates.sqlui.webapi.UpdateFeedbackSessionActionTest

[github-actions]

Hi @marifer-perezh, thank you for your interest in contributing to TEAMMATES!
However, your PR does not appear to follow our contribution guidelines:

• Description must reference the issue number the PR is fixing, e.g. Fixes #<issue-number> (or Part of #<issue-number> if the PR does not address the issue fully)

Please address the above before we proceed to review your PR.

[InfinityTwo]

@marifer-perezh thanks for your contributions. Your contribution looks like a short one, but it seems to have failed the checks. On initial looks, I have some comments for you which could help you move forward :)

• In your PR description, use Part of instead of Fixes so that we do not close the original issue. There should not be a space after #
• The errors for GitHub Action should have only failed for E2E tests, as that is a separate issue, which should be merged soon. Please fix the issues, tag me afterwards, and I'll review your PR after all related failures have passed

Thanks and happy coding!