(bug 47610) Update Wikidata test settings to use $wgWBClientSettings and $wgWBRepoSettings

* note: for settings defined in WikibaseLib, the variable stays the same: $wgWBSettings

Change-Id: If49b303890fa39a55e6fe3a9950ed5456f2bbbc3
Merge "(bug 47610) Update Wikidata test settings to use $wgWBClientSettings and $wgWBRepoSettings" into production