CI: use duneci-install-module and duneci-standard-test

.gitlab-ci.yml

 ---
 # Install external dependencies
 before_script:
-  - pushd /duneci/modules
-  - git clone https://git.imp.fu-berlin.de/agnumpde/dune-solvers.git
-  - dunecontrol --opts=/duneci/opts.gcc --only=dune-solvers all
-  - popd
+  - duneci-install-module https://git.imp.fu-berlin.de/agnumpde/dune-solvers.git
 
 dune:git--clang:
   image: duneci/dune:git
-  script:
-  - dunecontrol --opts=/duneci/opts.clang --current all
-  - dunecontrol --current make build_tests
-  - dunecontrol --current make test
+  script: duneci-standard-test --opts=/duneci/opts.clang
 
 dune:git--gcc:
   image: duneci/dune:git
-  script:
-  - dunecontrol --opts=/duneci/opts.gcc --current all
-  - dunecontrol --current make build_tests
-  - dunecontrol --current make test
+  script: duneci-standard-test