Rename packer template for compute 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

@@ -149,9 +149,9 @@ build_ssh_proxy_image:
         export PKR_VAR_image_name="${BUILD_TARGET}-${BUILD_DATE}"
       fi
     # packer commands
-    - packer init openstack-compute
-    - packer validate openstack-compute
-    - packer build -machine-readable openstack-compute | tee login_build.log
+    - packer init openstack-login
+    - packer validate openstack-login
+    - packer build -machine-readable openstack-login | tee login_build.log
     - export BUILT_LOGIN_IMAGE_ID=$(grep 'Image:' login_build.log | awk '{print $4}')
     - echo BUILT_LOGIN_IMAGE_ID=${BUILT_LOGIN_IMAGE_ID} | tee -a $CI_PROJECT_DIR/image.env
     # set image properties with repo state