Change compute reference to login

Because compute and login nodes are basically the same except login node does not need slurmd and we don't use compute image anywhere. So use it to build login image and change its references in CI script

.gitlab-ci.yml

@@ -281,7 +281,7 @@ deploy_login_node:
   tags:
     - build
   script:
-    - openstack image set --accept $login-${BUILD_DATE} || true
+    - openstack image set --accept $LOGIN_IMAGE_ID || true
     - FAILED=false
     - |
       cat > user_data.txt <<EOF