Update curl integration tests JSON assert
Update curl integration tests JSON assert

We changed how legacy commands output JSON for HTTP requests and
responses (e223fb760db14ce4a9b48cc6033a7614a6620272).

This commit updates `curl` integration tests to reflect the output
format, and also we change the test's assertion from using a regex match
to using Gomega's `MatchJSON` method.

cloudfoundry/cli,cloudfoundry/cli,cloudfoundry/cli