[sulfur] make it use the old, deprecated FileUpdates class

Sulfur will die anyway, no reason to port it over

sulfur/src/sulfur/__init__.py

@@ -38,6 +38,7 @@ if "/usr/lib/entropy/client" not in sys.path:
 if "/usr/lib/entropy/sulfur" not in sys.path:
     sys.path.insert(4, "/usr/lib/entropy/sulfur")
 
+os.environ["ENTROPY_CLIENT_ENABLE_OLD_FILEUPDATES"] = 1
 
 from entropy.exceptions import OnlineMirrorError, PermissionDenied
 import entropy.tools