Fix container builds failing on repo names with uppercase characters (#39208)

.github/workflows/build-container-image.yml

@@ -45,7 +45,8 @@ jobs:
           echo "PLATFORM_PAIR=${platform//\//-}" >> $GITHUB_ENV
           # Transform multi-line variable into comma-separated variable
           image_names=${PUSH_TO_IMAGES//$'\n'/,}
-          echo "IMAGE_NAMES=${image_names%,}" >> $GITHUB_ENV
+          image_names_split=${image_names%,}
+          echo "IMAGE_NAMES=${image_names_split,,}" >> $GITHUB_ENV
 
       - uses: docker/setup-buildx-action@8d2750c68a42422c14e847fe6c8ac0403b4cbd6f # v3
         id: buildx
@@ -160,11 +161,11 @@ jobs:
       - name: Create manifest list and push
         working-directory: ${{ runner.temp }}/digests
         run: |
-          echo "$PUSH_TO_IMAGES" | xargs -I{} \
+          echo "${PUSH_TO_IMAGES,,}" | xargs -I{} \
             docker buildx imagetools create $(jq -cr '.tags | map("-t " + .) | join(" ")' <<< "$DOCKER_METADATA_OUTPUT_JSON") \
               $(printf '{}@sha256:%s ' *)
 
       - name: Inspect image
         run: |
-          echo "$PUSH_TO_IMAGES" | xargs -i{} \
+          echo "${PUSH_TO_IMAGES,,}" | xargs -i{} \
             docker buildx imagetools inspect {}:${{ steps.meta.outputs.version }}