Investigate improving performance of _generate_doc() in hubmap_translator.py

[DerekFurstPitt]

Even with the new queue system for search-api, there are some performance issues affecting entities with a large number of associated entities (such as datasets or descendants).

Even though each association gets its own entry in the queue, when it comes time to generate each document, it still requires calls to entity api to get the ids for the associations.

Look into ways to minimize the number of calls made to entity-api, including potentially making a new endpoint in entity-api to consolidate some of these numerous calls.

[shirey]

organs-by-sections.tsv