remove enforcement of Wikibase client / repo load order

it's interfering with localisation cache rebuild for beta labs,
which uses master.

see also I9d22e46d which handles the extension settings in a new way
that is more leniant about load order.

Change-Id: I7a2e9a23e45b4c47301d629e1e6075b5863bade9
Merge "remove enforcement of Wikibase client / repo load order"