fix: move audio description toggle to safe shared module

[viv-helix]

Summary

Move the audio description feature toggle into a lightweight shared module to avoid import-time side effects during LMS initialization.

Problem

audio_description_enabled was being imported from cms.djangoapps.contentstore.toggles.

That module now imports search_api at module load time, which triggers early Django model initialization before apps/settings are fully ready. This caused LMS startup/runtime failures and exposed downstream initialization issues, including the ExtendedCasbinRule error.

The previous lazy import behavior was effectively masking these import-order dependencies.

Fix

• Move:

  • ENABLE_AUDIO_DESCRIPTION
  • audio_description_enabled

  from:

  • cms.djangoapps.contentstore.toggles

  to:

  • openedx.core.djangoapps.video_config.toggles

• Update LMS/CMS callers to import the toggle from the new shared module.

Result

The audio description toggle can now be safely imported from both LMS and CMS without pulling in search_api or triggering premature Django model loading.