Introduce EnrollmentTrackUserPartition.

cms/djangoapps/contentstore/course_group_config.py

cms/djangoapps/contentstore/tests/test_utils.py

cms/djangoapps/contentstore/utils.py

cms/djangoapps/contentstore/views/preview.py

cms/djangoapps/contentstore/views/tests/test_item.py

cms/envs/bok_choy.py

cms/envs/common.py

cms/envs/test.py

common/djangoapps/course_modes/admin.py

common/lib/xmodule/xmodule/course_module.py

common/lib/xmodule/xmodule/modulestore/mongo/base.py

common/lib/xmodule/xmodule/modulestore/split_mongo/split.py

common/lib/xmodule/xmodule/partitions/partitions.py

common/lib/xmodule/xmodule/partitions/partitions_service.py

...n/lib/xmodule/xmodule/partitions/tests/test_partitions.py

common/lib/xmodule/xmodule/split_test_module.py

common/lib/xmodule/xmodule/tests/test_split_test_module.py

lms/djangoapps/ccx/tests/test_field_override_performance.py

lms/djangoapps/course_api/blocks/tests/test_api.py

lms/djangoapps/course_blocks/transformers/user_partitions.py