Uses the same import path for instructor_task.models as edxapp

[pomegranited]

Fixes celery task error (ref TNL-5903):

RuntimeError: Conflicting 'instructortask' models in application 'instructor_task': <class 'lms.djangoapps.instructor_task.models.InstructorTask'> and <class 'instructor_task.models.InstructorTask'>.

Testing instructions

1. Ensure your devstack is updated to current master. The commit that introduced the conflict was 54d34e8.
2. Create a course, and import course.99Ob05.tar.gz.
3. Visit the Features > Instructor Tool unit, and note that you're able to filter and download data.

Reviewers

• haikuginger

[haikuginger]

👍 once tests are green.

• I tested this: I followed the testing instructions and verified that I didn't encounter any errors
• I read through the code
• I checked for accessibility issues N/A; no frontend changes
• Includes documentation N/A

[pomegranited]

@bradenmacdonald Do I need any more approvals before merging this PR, and tagging the updated version for the hotfix?

[bradenmacdonald]

@pomegranited No, one reviewer is fine here. Go ahead and merge.