largefiles: remove the second `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

@@ -579,7 +579,6 b' def updatelfiles('
             statuswriter(_(b'getting changed largefiles\n'))
             cachelfiles(ui, repo, None, lfiles)
 
-        with lfdirstate.changing_parents(repo):
             for lfile in lfiles:
                 update1 = 0