Fix prompt for nfs LAVA templates

Use specific prompts to match instead of just a single `#`.

Signed-off-by: Luis Araujo <luis.araujo@collabora.co.uk>

templates/group-nfs-tpl.yaml

@@ -80,9 +80,9 @@ actions:
         login_commands:
           - sudo su
       prompts:
-        - 'user@apertis:'
         - '\$ '
-        - '\# '
+        - '/home/user #'
+        - '/tmp #'
 
   - test:
       timeout: