largefiles: remove the first `changing_parents` in `updatelfiles`

Now that the `update_file` call have been migrated, we can drop the
semantically-wrong `changing_parents` context.

hgext/largefiles/lfcommands.py

@@ -517,7 +517,6 b' def updatelfiles('
             filelist = set(filelist)
             lfiles = [f for f in lfiles if f in filelist]
 
-        with lfdirstate.changing_parents(repo):
             update = {}
             dropped = set()
             updated, removed = 0, 0