Add Collection Meta Tag only when there is a collection.
[Provide a general summary of the issue in the title above]
Expected behavior
When we create a toc.xml file a collectionMeta tag should be added only when we have an assigned collection for this book. Right now we shouldn't pass it at all. because this throws an error when we ingest the Toc XML file to ncbi
Current behavior
when we create a toc.xml file a collectionMeta tag is placed every time
Possible solution
For now, just remove the collectionMeta tag