Identify scenarios where storyboard work can overwrite video conversions

A client has observed that if the storyboard work finishes after video conversion work for a Video asset, the vid:transcodedVideos property can be overwritten.

We should work to identify scenarios where this could happen, and consider code fixes to avoid it.

Potential causes or points of failure:

• Work separation (where storyboard work is processed on one node and conversions on a different node)
• MongoDB/DBS
• Storyboard work class