Merge pull request #13107 from edx/christina/delete-xblock-disable-config

common/djangoapps/xblock_django/admin.py

...ck_django/migrations/0004_delete_xblock_disable_config.py

common/djangoapps/xblock_django/models.py

common/test/db_cache/bok_choy_data_default.json

common/test/db_cache/bok_choy_migrations_data_default.sql

...cache/bok_choy_migrations_data_student_module_history.sql

common/test/db_cache/bok_choy_schema_default.sql

.../test/db_cache/bok_choy_schema_student_module_history.sql

common/test/db_cache/lettuce.db

common/test/db_cache/lettuce_student_module_history.db