fix: restore ARTIFACTS_TO_PUBLISH in release.sh to fix nightly releases (#9040)

hack: restore ARTIFACTS_TO_PUBLISH in release.sh to fix nightly releases

PR #9018 replaced ARTIFACTS_TO_PUBLISH with a local `artifacts` array,
but the vendored knative.dev/hack/release.sh relies on this global
variable for image signing, checksums generation, and artifact publishing.
With it unset, sign_release() had no files to process, breaking nightly
release jobs.

Author: creydr

hack/release.sh

@@ -66,10 +66,10 @@ function build_release() {
   local YAML_LIST="$(mktemp)"
   export TAG
   "$(dirname "$0")/generate-yamls.sh" "${REPO_ROOT_DIR}" "${YAML_LIST}"
-  mapfile -t artifacts < "${YAML_LIST}"
+  ARTIFACTS_TO_PUBLISH="$(cat "${YAML_LIST}" | tr '\n' ' ')"
   if (( ! PUBLISH_RELEASE )); then
     # Copy the generated YAML files to the repo root dir if not publishing.
-    cp "${artifacts[@]}" "${REPO_ROOT_DIR}"
+    cp ${ARTIFACTS_TO_PUBLISH} "${REPO_ROOT_DIR}"
   fi
 }