infra/gcp: improve lib_iam output
infra/gcp: improve lib_iam output

gcloud iam functions have noisy output, trim down to relevent info

- no error if role already removed
- no "policy updated" is policy didn't need to be updated
- diff before/after of policy changes in flat/concise format

kubernetes/k8s.io,kubernetes/k8s.io,kubernetes/k8s.io,kubernetes/k8s.io