Make setup_env_proxy immune to close ssh socket failure
Make setup_env_proxy immune to close ssh socket failure

- On a concourse container it is increasingly noticed that ssh socket
connection fails to close cleanly and results in script exiting with non
zero status due to set -e flag. This commit disables the set -e and
forces the ssh socket closure command to return 0 status.

cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release,cloudfoundry-incubator/bosh-vsphere-cpi-release