Parent container does not update when deleting a published component

[bradenmacdonald]

1. Create a component and a unit. Add the component to the unit.
2. Publish both the unit and the component.
3. Delete the component.
4. The component gets deleted but an error occurs when updating the container's search index entry. The traceback shown in this PR will appear in the CMS logs, and the "child component count" on the parent container will be wrong (not decreased).

[bradenmacdonald]

Fix: openedx/openedx-platform#38607