Fixed #19973 -- Replaced optparse by argparse in management commands

Thanks Tim Graham for the review.

tests/admin_scripts/management/commands/app_command.py

@@ -4,7 +4,6 @@ from django.core.management.base import AppCommand
 class Command(AppCommand):
     help = 'Test Application-based commands'
     requires_system_checks = False
-    args = '[app_label ...]'
 
     def handle_app_config(self, app_config, **options):
         print('EXECUTE:AppCommand name=%s, options=%s' % (app_config.name, sorted(options.items())))