MAINT: do not use saved images in cached job

.gitlab-ci.yml

@@ -42,14 +42,11 @@ build-testenv:
     - schedules
   script:
     - cd src/test/docker
-    - time docker load < /image-cache/caosdb-server-testenv.tar || true
     - docker login -u gitlab-ci-token -p $CI_JOB_TOKEN $CI_REGISTRY
       # use here general latest or specific branch latest...
     - docker build
       --pull
       -t $CI_REGISTRY_IMAGE .
-    - docker save $CI_REGISTRY_IMAGE > image.tar;
-          mv image.tar /image-cache/caosdb-server-testenv.tar;
     - docker push $CI_REGISTRY_IMAGE
 
 # Test: run unit tests of the server