This currently covers two cases:
- "kubectl list" (the regression from https://github.com/kubernetes/kubernetes/issues/107012)
- "kubectl get pods/no-such-pod" (no particular reason except that the output
should be deterministic)
In contrast to some other tests that check for strings inside the
output (run_deprecated_api_tests) or compare after
sorting (run_kubectl_version_tests), stdout, stderr and the return code must
match exactly.
This ensures that there is no extra, unexpected output and that the right
output stream is used.
