ValidationStatistics: Showing unreviewed pages depends on config

Special:UnreviewedPages does not exists on testwiki due to
wgFlaggedRevsProtection = true

Follow-Up: I63c2919587f858f91a2e9fe868b3cfb87b0650e0
Change-Id: I6c779b9ab425deaea9cab8ea4813563c095db889
Merge "ValidationStatistics: Showing unreviewed pages depends on config"