Kill remaining dependencies on lib and repo from DataModel

Change-Id: I36815e73321ae3ee00d1e4b54ebce4e349a33568
Removed dead test and inlined deprecated method

With this change, the DataModel tests now run without loading wikibase lib and repo

Change-Id: If00aa6ecb2e9d74116a9f5d1b2b8b5eb734ee17d