Add flag 'D' for wikidata edits on old watchlist/recentchanges

Using $wgRecentChangesFlag for this,
which was added with If69de05c to core.

Change-Id: Idc666db1b1b2b6656fa7b593f564f3f9c885f35f
Merge "Add flag 'D' for wikidata edits on old watchlist/recentchanges"