apertis-update-manager-automount: Add error messages

AUM has now more specific error messages when trying to use an incorrect
static update bundle.

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

test-cases/apertis-update-manager-automount.yaml

@@ -67,10 +67,11 @@ run:
     - "Reboot the system"
     - $ sudo journalctl -f --unit apertis-update-manager
     - "Plug the first USB flash drive with non-encrypted update bundle file in the device"
-    - "Wait around 1 min"
     - "The USB flash drive must mount correctly but must not start update, with a trace similar to:"
     - |
         >Feb 14 10:12:50 apertis apertis-update-[471]: mount added : /media/USB1
+        Feb 14 10:12:50 apertis apertis-update-[471]: Trying to use unencrypted bundle instead of encrypted bundle
+        Feb 14 10:12:50 apertis apertis-update-[471]: No static-update.bundle.enc found
     - "Remove the USB flash drive"
     - "Plug the third USB flash drive with encrypted update bundle file with unknown key in the device"
     - "The USB flash drive must mount correctly but must not start update, with a trace similar to:"