Fix list edits not being correctly picked up by solr updater

[cdrini]

Closes #9758 .

Technical

Testing

In a local dev environment,

1. docker compose logs --tail=10 -f solr-updater
2. Create a new list and save it
   • ✅ The list key appears in the solr-updater output
3. Go to http://localhost:8983/solr/openlibrary/update?commit=true to commit the changes to solr
   • ✅ http://localhost:8983/solr/#/openlibrary/query?q=type:list&q.op=OR&indent=true&wt=json&useParams= shows the list.

Screenshot

Stakeholders

@jediD83 @benbdeitch

[benbdeitch]

I tested this out on Gitpod, and it works like a charm. Excellent job, particularly with the refactoring!