Do not blocklist `GO` env vars (#563)
Do not blocklist `GO` env vars (#563)

I have had this be an issue 3 times recently - trying to set GOBUILDFLAGS, CGO_ENABLED, and GOPRIVATE.

I don't see any compelling reason to not allow these variables. The ones that users cannot set, like GOPATH, are things we overwrite anyways
istio/common-files,istio/common-files