Ensure Mentors completion displays 100% in the Dashboard

[curt-mitch]

Description

Mentors have the ability to complete a course project outside of the course platform. Therefore course completion values for mentors should not be calculated using the project completion rates.

Resolves https://github.com/OpenMined/openmined/issues/122

Affected Dependencies

N/A

How has this been tested?

manual testing in dev environment

Checklist

• [X] I have followed the Contribution Guidelines and Code of Conduct
• [X] I have commented my code following the OpenMined Styleguide
• [x] I have labeled this PR with the relevant Type labels
• [ ] My changes are covered by tests