Fix wrong alpha version for ValidateProxyRedirects
Fix wrong alpha version for ValidateProxyRedirects

This feature gate apparently never made it into 1.10 or 1.11
https://github.com/kubernetes/kubernetes/pull/69943

Kubernetes-commit: 9eb45d22a43f83c0ed957a580744ddbe1ef2dccd

kubernetes/apiserver,kubernetes/apiserver