Workaround issue with newer helm versions and the metrics api service

Helm 2.15.x and 3.0.x (before 3.0.2) have an issue where they throw an error if any of the apiservices aren't available, when doing a Helm install. https://github.com/helm/helm/issues/6361#issuecomment-550503455

For our gke-boostrap script, we are impacted by the kubemetrics service typically taking a few more seconds to startup than we have been giving it.