CI: fix artifact collection for diff-manifests

.gitlab-ci.yml

@@ -664,6 +664,9 @@ Manifest-diff:
     GIT_STRATEGY: "clone"
     GIT_CHECKOUT: "true"
     GIT_DEPTH: 500
+  artifacts:
+    paths:
+      - "/tmp/artifacts"
 
 SCHEDULED_CLOUD_CLEANER:
   stage: cleanup

test/cases/diff-manifests.sh

@@ -2,7 +2,7 @@
 
 set -euo pipefail
 
-artifacts="ci-artifacts"
+artifacts="/tmp/artifacts"
 mkdir -p "${artifacts}"
 
 # Colorful output.