Update .gitlab-ci.yml

.gitlab-ci.yml

 stages:
+  - pre-build
   - build
   - deploy
 
@@ -6,6 +7,18 @@ variables:
   # to avoid "fatal: git fetch-pack: expected shallow list"
   GIT_STRATEGY: clone
 
+pre-build:
+  stage: pre-build
+  tags:
+    - shell
+  script:
+        - docker login -u "${CI_REGISTRY_USER}" -p "${CI_REGISTRY_PASSWORD}" "${CI_REGISTRY}"
+        - docker build -t "${CI_REGISTRY_IMAGE}/vospace-maven-builder" -f maven-builder/Dockerfile .
+        - docker push "${CI_REGISTRY_IMAGE}/vospace-maven-builder"
+  only:
+    refs:
+      - test
+      
 build:
   stage: build
   tags:
@@ -30,7 +43,7 @@ build-test:
   stage: build
   tags:
     - docker
-  image: git.ia2.inaf.it:5050/vospace/vospace-helper-images/vospace-maven-builder
+  image: git.ia2.inaf.it:5050/vospace/vospace-parent/vospace-maven-builder
   variables:
     FILE_CATALOG_REPO_URL: "https://gitlab-ci-token:${CI_JOB_TOKEN}@www.ict.inaf.it/gitlab/vospace/vospace-file-catalog.git"
   script: