Use DOCKER_IMAGE_NAME in promote step

Signed-off-by: Federico Busetti <729029+febus982@users.noreply.github.com>

Author: febus982

.gitlab_ci/deploy.yml

@@ -1,7 +1,7 @@
 promote-dev:
   stage: deploy
   variables:
-    DOCKER_IMAGE_TAG_PREFIX: "http-"
+    DOCKER_IMAGE_NAME: $CI_PROJECT_NAME-http
   rules:
     # We run the pipeline only on merge requests or the `main` branch
     - if: $CI_COMMIT_REF_NAME == $CI_DEFAULT_BRANCH