Artifactory rest calls can return HTTP 200 despite failures

[philwebb]

The curl commands we issue to artifactory can sometimes fail without returning a correct HTTP status code. Most recently this happened with a call to api/v2/distribution/distribute which returned:

{"message":"RBv2 spring:spring-release-bundles-v2/<redacted> was not found","status_code":404}

For extra protection, we can check that the response JSON contains at least one expected field.