refactor: Remove set_course_discussion_settings helper

...djangoapps/discussion/django_comment_client/base/tests.py

...goapps/discussion/django_comment_client/tests/group_id.py

...apps/discussion/django_comment_client/tests/test_utils.py

...jangoapps/discussion/django_comment_client/tests/utils.py

lms/djangoapps/discussion/rest_api/serializers.py

lms/djangoapps/discussion/views.py

openedx/core/djangoapps/course_groups/models.py

openedx/core/djangoapps/course_groups/tests/helpers.py

openedx/core/djangoapps/django_comment_common/models.py

openedx/core/djangoapps/django_comment_common/tests.py

openedx/core/djangoapps/django_comment_common/utils.py