fix: Run CMS migrations on CMS container (#1048)

I think this was just a copy-paste error. It worked OK most of the time,
but it failed for me recently. I had only run `make requirements` in
`make studio-shell` and then tried to `make studio-migrate`. It failed
because the management command ran on lms and the migration depended on
newer requirements.

Author: timmc-edx

Makefile

@@ -259,8 +259,8 @@ $(foreach db_service,$(DB_SERVICES_LIST),\
 dev.migrate: | $(_db_migration_targets) ## Run migrations for applicable default services.
 
 dev.migrate.studio:
-	docker-compose exec -T -u root lms bash -e -c '/edx/app/edxapp/venvs/edxapp/bin/python manage.py cms showmigrations --database default --traceback --pythonpath=. --settings devstack_docker'
-	docker-compose exec -T -u root lms bash -e -c '/edx/app/edxapp/venvs/edxapp/bin/python manage.py cms migrate --database default --noinput --traceback --pythonpath=. --settings devstack_docker'
+	docker-compose exec -T -u root cms bash -e -c '/edx/app/edxapp/venvs/edxapp/bin/python manage.py cms showmigrations --database default --traceback --pythonpath=. --settings devstack_docker'
+	docker-compose exec -T -u root cms bash -e -c '/edx/app/edxapp/venvs/edxapp/bin/python manage.py cms migrate --database default --noinput --traceback --pythonpath=. --settings devstack_docker'
 
 dev.migrate.lms:
 	docker-compose exec -T -u root lms bash -e -c '/edx/app/edxapp/venvs/edxapp/bin/python manage.py lms showmigrations --database default --traceback --pythonpath=. --settings devstack_docker'