Default instructor role to non-editing teacher instead of editing teacher [otf:1109]

This is a set of requests:

https://github.com/KAPx/kapx-site/pull/300
https://github.com/KAPx/kapx-courses/pull/279
https://github.com/KAPx/moodle-local_wskapx/pull/32
https://github.com/KAPx/moodle-local_ltiprovider/pull/6