ci: packer cache script should fail never to help to cache dependencies (#806)

Author: v1v

.ci/packer_cache.sh

@@ -1,7 +1,7 @@
 #!/usr/bin/env bash
 source /usr/local/bin/bash_standard_lib.sh
 
-JAVA_HOME=$HOME/.java/java10 ./mvnw clean verify
+JAVA_HOME=$HOME/.java/java10 ./mvnw clean verify --fail-never
 
 (retry 2 docker pull docker.elastic.co/observability-ci/weblogic:12.2.1.3-dev) \
   && docker tag docker.elastic.co/observability-ci/weblogic:12.2.1.3-dev store/oracle/weblogic:12.2.1.3-dev