Update Ubuntu20 image for Azure using the right URN

Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>

hackfest_multivdu_vnf/hackfest_multivdu_vnfd.yaml

@@ -38,7 +38,7 @@ vnfd:
     vim-type: aws
   - id: ubuntu20.04-azure
     name: ubuntu20.04-azure
-    image: Canonical:UbuntuServer:20.04-LTS:latest
+    image: Canonical:0001-com-ubuntu-server-focal:20_04-lts:latest
     vim-type: azure
   vdu:
   - id: mgmtVM