Pipeline - Adding a step to clean up untagged images

Fixed: #2337

.github/workflows/pr-close-delete-env.yml

@@ -114,6 +114,13 @@ jobs:
             Write-Host '❌ Key Vault not found'
           }
 
+      - name: Delete all untagged images
+        run: |
+          $untaggedDigests = az acr manifest list-metadata -r  ${{ env.ACR_NAME }} -n `
+          ${{ env.IMAGE_NAME }} --query "[?tags==null].digest" -o tsv | `
+          %{ az acr repository delete -n ${{ env.ACR_NAME }} -t ${{ env.IMAGE_NAME }}@$_ --yes}
+          Write-Host "✅ All untagged images have been deleted"
+
       - name: ACR - Delete image
         run: |
           $imageTagWithPrefix = '${{ env.SLOT_PREFIX }}${{ matrix.SLOT_NAME}}'