WikibaseClient now needs to know the entityNamespaces setting for it's repo (e.g. Wikidata).
For commons, that means to set:
$wgWBClientSettings['entityNamespaces']['wikibase-item'] = NS_MAIN;
When we enable MediaInfo, then commons will also become a repo and obviously can't have items in the main namespace. (and maybe won't have items at all?)
so we need to unset the above (and then some client stuff breaks?) or make it explicit it's for client only.