[FR] Reuse gcloud proxy setup

[tarrade]

Right now it ignore the proxy configuration of gcloud and we need do the following:

https_proxy='http://URLPROXY.intraxa:2222' gcloud run services proxy xxx --port=6006 --region=europe-west6

Will be great if it could reuse the proxy info that we have to setup for for gcloud:

[proxy]
  address: [PROXYURL] (property file)
  port: [2222] (property file)
  type: [http] (property file)