largefiles: replace use of synclfdirstate with drop

Replace calling a complex function with a simple dedicated one

Differential Revision: https://phab.mercurial-scm.org/D11113

hgext/largefiles/lfcommands.py

@@ -565,20 +565,19 def updatelfiles(
         # largefile processing might be slow and be interrupted - be prepared
         lfdirstate.write()
 
-        with lfdirstate.parentchange():
             if lfiles:
                 lfiles = [f for f in lfiles if f not in dropped]
 
                 for f in dropped:
                     repo.wvfs.unlinkpath(lfutil.standin(f))
-
                     # This needs to happen for dropped files, otherwise they stay in
                     # the M state.
-                    lfutil.synclfdirstate(repo, lfdirstate, f, normallookup)
+                lfdirstate._drop(f)
 
                 statuswriter(_(b'getting changed largefiles\n'))
                 cachelfiles(ui, repo, None, lfiles)
 
+        with lfdirstate.parentchange():
             for lfile in lfiles:
                 update1 = 0