Blender Git Loki

Fix T88237: Prefetch crash on rendering scene strip

Prefetch needs to avoid rendering scene strips, because

- Rendering in background needs own dependency graph, which fails to
initialize from evaluated data.
- This locks UI and can make it unresponsive for long time periods.

In T88237 prefetch failed to avoid scene strip, because of effect strip
was attached to scene strip.

Ensure, that no effect that is attached to scene strip either directly
or indirectly would be rendered.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D11247