Reverse prebuilt multi-object yamls in k8s_object's delete

[mattmoor]

This is related to this issue with k8s_objects.

This manifests when the input to k8s_object is a multi-document yaml file delimited by ---, such as the Istio release.

In the case of Istio what happens is that they create the CRDs before instances of the CRDs, otherwise kubectl create would fail.

However, when you kubectl delete this file, you run into problems because (evaluating in the same order) you delete the CRD definition before its instances, and so the former cascades the deletion and the latter result in 404 errors.