CI: yml modification for pipeline

.gitlab-ci.yml

@@ -45,13 +45,22 @@ debian-build:
   extends: .general
   only: [merge_requests]
   stage: build
-  image: registry.orfeo-toolbox.org/gbonnefille/otb-build-env/otb-debian-native:unstable
+  image: $BUILD_IMAGE_REGISTRY/otb-debian-native:unstable
   script:
     - ctest -VV -S CI/main_ci.cmake -DIMAGE_NAME:string=debian-unstable-gcc
 
-build:ubuntu-llvm:
+.common-build:
   extends: .general
   stage: build
   image: $BUILD_IMAGE_REGISTRY/otb-ubuntu-shark:18.04
   script:
     - ctest -VV -S CI/main_ci.cmake -DIMAGE_NAME:string=ubuntu-18.04-llvm-shark
+
+build:ubuntu-llvm:
+  only: [merge_requests]
+  extends: .common-build
+
+build:ubuntu-llvm-wip:
+  except: [merge_requests]
+  extends: .common-build
+