Introduce container_registry for image prefix

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Change-Id: I80067f53aa2b63286b654fff782f0f7b65a2d050
diff --git a/images/ovn/Dockerfile b/images/ovn/Dockerfile
index 4859b29..c8b7729 100644
--- a/images/ovn/Dockerfile
+++ b/images/ovn/Dockerfile
@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: Apache-2.0
 # Atmosphere-Rebuild-Time: 2024-06-25T22:49:25Z
 
+ARG REGISTRY
 ARG RELEASE
 
 FROM harbor.atmosphere.dev/docker.io/library/golang:1.20 AS ovn-kubernetes
@@ -13,7 +14,7 @@
 go build -o /usr/bin/ovn-kube-util ./cmd/ovn-kube-util
 EOF
 
-FROM harbor.atmosphere.dev/library/openvswitch:${RELEASE}
+FROM ${REGISTRY}/openvswitch:${RELEASE}
 ARG TARGETPLATFORM
 ADD --chmod=755 https://dl.k8s.io/release/v1.29.3/bin/${TARGETPLATFORM}/kubectl /usr/local/bin/kubectl
 ARG OVN_SERIES=24.03