Add GOPATH/bin to PATH env var in ci-test.sh
Add GOPATH/bin to PATH env var in ci-test.sh

HNC: This env var is not set in Prow (as stated on this issue
https://github.com/kubernetes/test-infra/issues/9469, therefore,
it needs be set manually.

kubernetes-sigs/multi-tenancy,kubernetes-sigs/multi-tenancy