Old django manage.py interface removed

There was a toggle to switch back ot ancient one, but new is pretty stable, so we do not need old one anymore

platform/util/resources/misc/registry.properties

@@ -403,8 +403,6 @@ tabs.alphabetical=false
 remote.changelist.management.available=false
 
 python.import.always.ask=false
-# Use new manage.py interface like in PY-11855. See com.jetbrains.django.manage.deperecated. TODO: Remove when new manage py will be released
-python.django.use_new_manage_py_interface=true
 # Number of seconds to wait for manage.py list commands
 python.django.timeout=15
 introduce.variable.prefer.statements=false