Improve CCX course publishing to avoid cross-process course_published signals

Description:

While working on https://github.com/openedx/edx-platform/pull/36128, we attempted to fix an issue where CCX courses failed to load with “course outline not found” errors. The fix added cms.djangoapps.contentstore.apps.ContentstoreConfig to LMS production settings so that course publish signals would trigger properly when creating a CCX.

However, this approach relies on a cross-process signal emission: the CMS emits course_published signals, which then spawn Celery workers on the LMS side. This pattern has caused multiple hard-to-debug issues in the past, especially with block transformers and environments where Celery is run in-process.

Suggested improvement (per @ormsbee):
Instead of enabling CMS code in the LMS, we should move CCX course publishing logic into CMS directly, avoiding the cross-process signal pattern entirely.

Next steps:

• Investigate how CCX course publishing is currently implemented.
• Refactor to run publishing within CMS, aligning with Dave’s suggestion.
• Ensure that CCX course creation triggers the necessary updates without relying on LMS signal handling.

Context:

Original PR: #36128

cc: @ormsbee @kdmccormick @pdpinch

Start with original PR #36128 and trace how CCX course creation currently reaches course publishing through CMS and LMS signals. Investigate the CMS and LMS production-settings involvement, then verify that CCX creation updates the course without cross-process signal handling or in-process Celery issues.