Do not add A-Z PI within each part that is itself sorted A-Z
Expected behaviour
A-Z PIs are ONLY added in a flat toc.xml that does not have any parts.
Current behaviour
A-Z PIs are being added in toc.xml within each part that contradicts the functionality of that feature on our site(s) display.
Steps to reproduce
Compare to something similar structurally on our live site:
https://www.ncbi.nlm.nih.gov/books/NBK278943/
Priority
Y, for processing