Revert "don't delete dangling facts when deleting cards" hack

We don't need this any more as we do conflict handling.

This reverts commit 880219567e.

anki/deck.py

@@ -1237,6 +1237,8 @@ where facts.id not in (select distinct factId from cards)""")
         # delete unused
         self.s.statement("delete from tags where id in %s and priority = 2" %
                          ids2str(unused))
+        # remove any dangling facts
+        self.deleteDanglingFacts()
         self.rebuildCounts()
         self.refresh()
         self.flushMod()