This is really two separate things:
1. Fix the notes retirement endpoint to generate the correct notes API
url "/api/v1/annotations/" rather than the nonexistent "/api/v1/".
2. Update the API params to use "user" rather than "user_id". This
depends on another PR in edx/edx-notes-api to make the corresponding
change on the API side. This is required because "user" is the
hard-coded key that the permissions class uses to check the JWT token
user.