Fix manifest push failure handling (#2193)

Signed-off-by: Bartosz Bezak <bartosz@stackhpc.com>

Author: bbezak

releasenotes/notes/multiarch-manifests-pipefail-9b860f83d0f93f1e.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Fixes CI multiarch manifest creation by setting ``pipefail`` in the
+    manifest script. Failures from ``docker manifest create`` or
+    ``docker manifest push`` now fail the job even when piped to ``tee``.

tools/multiarch-manifests.sh

@@ -1,15 +1,16 @@
 #!/usr/bin/env bash
 # Script used by the Image build workflow to build & push multiarch manifests.
 
-set -ex
+set -o errexit
+set -o xtrace
+set -o pipefail
 
 mkdir -p logs
 images=$(cat all-pushed-images.txt | sort | uniq)
 
 # Filter out Ubuntu and Rocky Bifrost images
 manifest_images=$(echo "$images" \
-  | grep -E '.*-(amd64|aarch64)$' \
-  | sed -E 's/-(amd64|aarch64)$//' \
+  | sed -nE 's/-(amd64|aarch64)$//p' \
   | sort | uniq)
 
 if [ -z "$manifest_images" ]; then