Fix kubebuilder installation in the build root Dockerfile

Update the base.Dockerfile and fix the kubebuilder installation. That
vanity URL is no longer correctly serving the v2.3.1 release tar.gz
file. Update to instead curl directly from the github releases URL.

Author: timflannagan

base.Dockerfile

@@ -2,11 +2,12 @@
 
 FROM openshift/origin-release:golang-1.13
 
-# Install test dependencies
+ARG KUBEBUILDER_RELEASE=2.3.1
 RUN yum install -y skopeo && \
     export OS=$(go env GOOS) && \
     export ARCH=$(go env GOARCH) && \
-    curl -L "https://go.kubebuilder.io/dl/2.3.1/${OS}/${ARCH}" | tar -xz -C /tmp/ && \
-    mv /tmp/kubebuilder_2.3.1_${OS}_${ARCH}/ /usr/local/kubebuilder && \
+    curl -L "https://github.com/kubernetes-sigs/kubebuilder/releases/download/v${KUBEBUILDER_RELEASE}/kubebuilder_${KUBEBUILDER_RELEASE}_${OS}_${ARCH}.tar.gz" | tar -xz -C /tmp/ && \
+    mv /tmp/kubebuilder_${KUBEBUILDER_RELEASE}_${OS}_${ARCH}/ /usr/local/kubebuilder && \
     export PATH=$PATH:/usr/local/kubebuilder/bin && \
+    kubebuilder version && \
     echo "Kubebuilder installation complete!"