ci: add full-node tests (#920)

diff --git a/images/horizon/Earthfile b/images/horizon/Earthfile
index fe9ac5f..6d0d246 100644
--- a/images/horizon/Earthfile
+++ b/images/horizon/Earthfile
@@ -1,5 +1,6 @@
 VERSION 0.7
 
+ARG --global REGISTRY=ghcr.io/vexxhost/atmosphere
 ARG --global PROJECT=horizon
 ARG --global RELEASE=2023.2
 ARG --global PROJECT_REF=3c6029cd94846235e25058b71522c13556f41f58
@@ -33,5 +34,5 @@
   DO ../+APT_INSTALL \
     --PACKAGES "apache2 gettext libapache2-mod-wsgi-py3"
   SAVE IMAGE --push \
-    ghcr.io/vexxhost/atmosphere/${PROJECT}:${RELEASE} \
-    ghcr.io/vexxhost/atmosphere/${PROJECT}:${PROJECT_REF}
+    ${REGISTRY}/${PROJECT}:${RELEASE} \
+    ${REGISTRY}/${PROJECT}:${PROJECT_REF}