In https://gerrit.wikimedia.org/r/#/q/I21413771b90466de4ae45a8b160d4c4f1f341f93,
we stopped logging a warning for when an entity isn't found for a given
revision.
We want to keep logging a warning for Wikidata, but let other users of Wikibase turn that warning off through configuration in case they have more expected and frequent use-cases hitting this path. See T229482: PHP Warning: Wikibase\Lib\Store\Sql\WikiPageEntityRevisionLookup::getEntityRevision: Entity not loaded for such case we faced on Commons.