Remove events from two endpoints and adjust a third one

[lordblendi]

• EventTemplates/list: we don't need to include all this data in the results as we don't use it and it makes the application slow.
• Deliverables/get: we already have the data in the relationships so this is duplicate here
• ExerciseTypes/get: students should get the details here. I saw an error locally for this even on the master branch.