Introduce container_registry for image prefix

Skip-Release-Notes
Change-Id: I80067f53aa2b63286b654fff782f0f7b65a2d050
diff --git a/images/manila/Dockerfile b/images/manila/Dockerfile
index 09d2bf9..b2c6713 100644
--- a/images/manila/Dockerfile
+++ b/images/manila/Dockerfile
@@ -1,9 +1,10 @@
 # SPDX-License-Identifier: Apache-2.0
 # Atmosphere-Rebuild-Time: 2024-06-28T12:14:26Z
 
+ARG REGISTRY
 ARG RELEASE
 
-FROM harbor.atmosphere.dev/library/openstack-venv-builder:${RELEASE} AS build
+FROM ${REGISTRY}/openstack-venv-builder:${RELEASE} AS build
 ARG MANILA_GIT_REF=c0fc23a39f87629b59fae7bbf46f70e3e1b459cd
 ADD --keep-git-dir=true https://opendev.org/openstack/manila.git#${MANILA_GIT_REF} /src/manila
 RUN git -C /src/manila fetch --unshallow
@@ -15,7 +16,7 @@
         /src/manila
 EOF
 
-FROM harbor.atmosphere.dev/library/openstack-python-runtime:${RELEASE}
+FROM ${REGISTRY}/openstack-python-runtime:${RELEASE}
 RUN <<EOF bash -xe
 apt-get update -qq
 apt-get install -qq -y --no-install-recommends \