remove users/$user/is_admin metadata, directly write sudo_commands instead

bundles/users/metadata.py

@@ -36,7 +36,7 @@ def add_users_from_json(metadata):
         if config.get('is_admin', False) or uname in metadata_users:
             users[uname] = {
                 'ssh_pubkey': set(config['ssh_pubkey']),
-                'is_admin': config.get('is_admin', False),
+                'sudo_commands': ['ALL'],
             }
 
     # Then, run again to get all 'to be deleted' users