Disable openthread in chef.py

Author: erwinpan1

examples/chef/chef.py

@@ -801,6 +801,7 @@ def main() -> int:
                 'import("${chip_root}/config/standalone/args.gni")',
                 'chip_shell_cmd_server = false',
                 'chip_build_libshell = true',
+                'chip_enable_openthread = false',
                 'chip_config_network_layer_ble = false',
                 'chip_device_project_config_include = "<CHIPProjectAppConfig.h>"',
                 'chip_project_config_include = "<CHIPProjectAppConfig.h>"',