Change CI pipeline

• merge build and test targets: this avoids recompiling most of the same files twice in the same conditions (build have been removed)
• remove gcc-debug targets. Actually gcc-coverage use debug options

This should lead to faster ci runs

.gitlab-ci/clang10-mpi-debug.yml

-build:clang10-mpi-debug:
-  image: localhost:5000/ubuntu_clang10_mpi
-  stage: build
-  needs: []
-  script:
-    - mkdir -p build/clang10-debug-mpi
-    - cd build/clang10-debug-mpi
-    - CXX=clang++-10 CC=clang-10 cmake ../.. -DCMAKE_BUILD_TYPE=Debug
-    - make pugs
-  cache:
-    key: "${CI_COMMIT_REF_SLUG}-clang10-debug-mpi"
-    paths:
-      - build/clang10-debug-mpi
-    untracked: true
-
 test:clang10-mpi-debug:
   image: localhost:5000/ubuntu_clang10_mpi
   stage: test
-  needs: ["build:clang10-mpi-debug"]
+  needs: []
   script:
     - mkdir -p build/clang10-debug-mpi
     - cd build/clang10-debug-mpi
     - CXX=clang++-10 CC=clang-10 cmake ../.. -DCMAKE_BUILD_TYPE=Debug
-    - make test
+    - make
+    - make check
   cache:
     key: "${CI_COMMIT_REF_SLUG}-clang10-debug-mpi"
     paths: