Update GKE section to use inline gcloud command
Update GKE section to use inline gcloud command

the `gcloud` tool has a rich query and value extraction mechanism which means we should not need to resort to using `grep` which is brittle because it is parsing the human consumable format that can change any time Google wants.
datawire/ambassador,datawire/ambassador,datawire/ambassador,datawire/ambassador,datawire/ambassador