add back rhel to build single image

Author: AlexFenlon

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

@@ -95,6 +95,7 @@ jobs:
           echo "::add-mask::$PLUS_CREDS"
           echo $PLUS_CREDS | jq -r '.crt' > nginx-repo.crt
           echo $PLUS_CREDS | jq -r '.key' > nginx-repo.key
+          az keyvault secret show --name rhel-creds --vault-name ${{ secrets.NIC_KEYVAULT_NAME }} --query value -o tsv > rhel_license
         if: ${{ contains(inputs.target, 'plus') }}
 
       - name: Fetch Cached Binary Artifacts
@@ -142,5 +143,5 @@ jobs:
 
       - name: Clean up secrets
         run: |
-          rm -f nginx-repo.crt nginx-repo.key
+          rm -f nginx-repo.crt nginx-repo.key rhel_license
         if: always()