The custom metrics stackdriver adapter ClusterRole object should not be using a namespace

[iangelov]

I was deploying the custom metrics stackdriver adapter to a GKE cluster and the deployment tool that I was using failed during the validation step. This was caused by the fact that the ClusterRole object is namespaced in the deployment manifest, however this a non-namespaced resource[1][2]. I'm bringing it up as an issue since this prevents me from readily taking the manifest and deploying it with custom tooling (read: not kubectl).

I'm happy to submit a PR to address that.

[CatherineF-dev]

Hi @iangelov, thanks for reporting this! Feel free to create a PR!