ENH: use cached image building

.gitlab-ci.yml

@@ -23,10 +23,6 @@ variables:
   CI_REGISTRY_IMAGE: $CI_REGISTRY/caosdb-mysqlbackend-testenv:latest
   # When using dind, it's wise to use the overlayfs driver for
   # improved performance.
-  DOCKER_DRIVER: overlay2
-
-services:
-  - docker:19.03.0-dind
 
 image: $CI_REGISTRY_IMAGE
 stages:
@@ -47,12 +43,12 @@ trigger_build:
 
 # Build a docker image in which tests for this repository can run
 build-testenv:
-  tags: [ docker ]
+  tags: [ cached-dind ]
   image: docker:19.03
   stage: setup
   script: 
     - cd .docker
-    - docker login -u testuser -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
+    - docker login -u indiscale -p $CI_REGISTRY_PASSWORD $CI_REGISTRY
       # use here general latest or specific branch latest...
     - docker pull $CI_REGISTRY_IMAGE || true
     - docker build