ci(gitlab-ci): use CI_JOB_MANUAL for container setup

.gitlab-ci.yml

@@ -88,10 +88,10 @@ setup:containers:frontend:
     - REGISTRY_DESTINATION=${CI_REGISTRY_IMAGE}/frontend/${CI_COMMIT_REF_SLUG}:${FRONTEND_IMAGE_VERSION}
     - IMAGE_EXISTS=`curl "${CI_API_V4_URL}/projects/${CI_PROJECT_ID}/registry/repositories?tags=true" | grep \""${REGISTRY_DESTINATION}"\"`
     - echo ${IMAGE_EXISTS}
-    - echo ${FORCE_REBUILD_IMAGE}
-    - test ${FORCE_REBUILD_IMAGE} == true && echo "Force rebuilding container."
+    - echo ${CI_JOB_MANUAL}
+    - test ${CI_JOB_MANUAL} == true && echo "Force rebuilding container."
     - >
-      if [ -z ${IMAGE_EXISTS} -o ${FORCE_REBUILD_IMAGE} == true ] ; then
+      if [ -z ${IMAGE_EXISTS} -o ${CI_JOB_MANUAL} == true ] ; then
         echo "Building image..."
         buildah bud -t ${IMAGE_TAG} --build-arg PROJECT_DIR=${CI_PROJECT_DIR} --volume ${CI_PROJECT_DIR}:/tmp/${CI_PROJECT_DIR} --file docker/frontend/Dockerfile
         buildah push --creds "${CI_REGISTRY_USER}:${CI_JOB_TOKEN}" ${IMAGE_TAG} ${REGISTRY_DESTINATION}
@@ -100,11 +100,6 @@ setup:containers:frontend:
       fi
   rules:
     - when: always
-      variables:
-        FORCE_REBUILD_IMAGE: false
-    - when: manual
-      variables:
-        FORCE_REBUILD_IMAGE: true
 
 setup:containers:backend: &containers-backend
   stage: setup