Merge branch '1834-test-data-lfs-registry' into 'develop'

Factorize build images specification

See merge request orfeotoolbox/otb!429

.gitlab-ci.yml

@@ -9,6 +9,7 @@
 # GIT_STRATEGY=fetch (https://gitlab.com/gitlab-org/gitlab-runner/issues/3318)
 
 variables:
+  BUILD_IMAGE_REGISTRY: $CI_REGISTRY/gbonnefille/otb-build-env
   DOCKER_DRIVER: overlay2
   GIT_DEPTH: "3"
   # Disable automatic checkout to let us fetch LFS before
@@ -36,13 +37,13 @@ native-build:
   extends: .general
   only: [merge_requests]
   stage: build
-  image: registry.orfeo-toolbox.org/gbonnefille/otb-build-env/otb-ubuntu-native:18.04
+  image: $BUILD_IMAGE_REGISTRY/otb-ubuntu-native:18.04
   script:
     - ctest -VV -S CI/main_ci.cmake -DIMAGE_NAME:string=ubuntu-18.04-gcc
 
 build:ubuntu-llvm:
   extends: .general
   stage: build
-  image: registry.orfeo-toolbox.org/gbonnefille/otb-build-env/otb-ubuntu-shark:18.04
+  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