removed leftover nginx build

.gitlab-ci.yml

@@ -20,11 +20,3 @@ build_app:
     - docker pull $CI_REGISTRY_IMAGE:test || true
     - docker build --cache-from $CI_REGISTRY_IMAGE:test -t $IMAGE_TAG_APP .
     - docker push $IMAGE_TAG_APP
-
-build_nginx:
-  stage: build
-  when: manual
-  script:
-    - docker pull $CI_REGISTRY_IMAGE:test-nginx || true
-    - docker build --cache-from $CI_REGISTRY_IMAGE:test-nginx -t $IMAGE_TAG_NGINX . -f Dockerfile.nginx
-    - docker push $IMAGE_TAG_NGINX