[#13304] Refactor GetFeedbackQuestionsActionTest to use BaseActionTest

[AlanRQiu]

Part of #13304

Description
This PR refactors GetFeedbackQuestionsActionTest.java to use the abstracted access control test methods migrated to BaseActionTest.java.

Changes
Refactored Access Control: Replaced manual logic with verifyOnlyInstructorsOfTheSameCourseCanAccess to handle multi-role permission checks automatically.

Added Mock Logic: Included when(...).thenReturn(...) for feedback session retrieval to satisfy internal getNonNullSqlFeedbackSession checks during the action's execution.

Standardized Parameters: Created a getActionParams() helper method to reduce redundancy across success and failure test cases.

Updated Failure Tests: Migrated manual parameter failure assertions to use the base class verifyHttpParameterFailure() method.

Verification Results
Ran unit tests locally using:
.\gradlew.bat

[github-actions]

Hi @AlanRQiu, 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.

[samuelfangjw]

Thank you for your interest in contributing, please ensure all tests pass before we go ahead and review this PR.

[samuelfangjw]

Closing due to inactivity to keep things tidy and so others can work on it. If you’d like to continue working on it, feel free to reopen the PR or create a new one anytime. Thanks for your contribution!