FIX: use docker caching

.gitlab-ci.yml

@@ -22,7 +22,6 @@ variables:
    CI_REGISTRY_IMAGE: $CI_REGISTRY/caosdb-advanced-testenv
    # When using dind, it's wise to use the overlayfs driver for
    # improved performance.
-   DOCKER_DRIVER: overlay2
 
 services:
   - docker:19.03.0-dind
@@ -63,7 +62,7 @@ test:
     expire_in: 1 week
 
 build-testenv:
-  tags: [notls]
+  tags: [cached-dind]
   image: docker:18.09
   stage: setup
   only:
@@ -89,7 +88,7 @@ cert:
       - cd .docker
       - CAOSHOSTNAME=caosdb-server ./cert.sh
 style:
-  tags: [notls]
+  tags: [docker]
   stage: style
   image: $CI_REGISTRY_IMAGE:latest
   script: