Use PR docker image in cluster

Author: acogoluegnes

.github/workflows/test-pr.yml

@@ -44,6 +44,8 @@ jobs:
         run: docker stop rabbitmq && docker rm rabbitmq
       - name: Start cluster
         run: ci/start-cluster.sh
+        env:
+          RABBITMQ_IMAGE: pivotalrabbitmq/rabbitmq:pr-13672-otp27
       - name: Test against cluster
         run: ./mvnw test -Dtest="*ClusterTest" -Drabbitmqctl.bin=DOCKER:rabbitmq0
       - name: Stop cluster