fetch worker script: abort if response status is not ok (wpt)

{"fail_fast": false, "matrix": [{"name": "Linux (WPT)", "workflow": "linux", "wpt": true, "profile": "release", "unit_tests": false, "build_libservo": false, "bencher": false, "build_args": "", "wpt_args": "", "number_of_wpt_chunks": 20}]}

Author: Gae24