Prevent students from requesting competency review

Currently, we have one competency linked to each course which is completed on course completion. This process is automatic.

Therefore, students should not be able to request review for competencies as currently happening.

<img width="615" alt="github" src="https://user-images.githubusercontent.com/7384198/82639172-80098380-9c08-11ea-8206-08ebec2c07dd.png">