Investigate use of QLever endpoint in SF

[ross-spencer]

Anecdotally, qlever may be more performant. It's not really a huge concern for the Wikidata integration and Siegfried, but it may be worth a go: https://qlever.dev/wikidata

NB. more a concern for Siegfried is the collection of provenance information from MediaWiki itself. Still, this is no longer a huge deal-breaker.

NB. also, check out the other endpoints from qlever -- I'm not even sure what half of them are!