Tutorials: add support for 'default'/"empty" DNN to CN5G configuration file

Add support for 'default' DNN to CN5G configuration file (that will also be used when DNN is not available, "empty" DNN). This configuration will allow most of the COTS UE to get PDUSession without any APN configuration made by the user

The 'default'/"empty" DNN configuration support was added in https://gitlab.eurecom.fr/oai/cn5g/oai-cn5g-amf/-/merge_requests/343

doc/tutorial_resources/oai-cn5g/conf/config.yaml

@@ -177,6 +177,7 @@ smf:
           - dnn: "oai"
           - dnn: "openairinterface"
           - dnn: "ims"
+          - dnn: "default"
   local_subscription_infos:
     - single_nssai: *embb_slice
       dnn: "oai"
@@ -196,6 +197,12 @@ smf:
         5qi: 9
         session_ambr_ul: "10Gbps"
         session_ambr_dl: "10Gbps"
+    - single_nssai: *embb_slice
+      dnn: "default"
+      qos_profile:
+        5qi: 9
+        session_ambr_ul: "10Gbps"
+        session_ambr_dl: "10Gbps"
 
 upf:
   support_features:
@@ -211,6 +218,7 @@ upf:
           - dnn: "oai"
           - dnn: "openairinterface"
           - dnn: "ims"
+          - dnn: "default"
 
 ## DNN configuration
 dnns:
@@ -225,3 +233,7 @@ dnns:
     pdu_session_type: "IPV4V6"
     ipv4_subnet: "10.0.9.0/24"
     ipv6_prefix: "2001:1:2::/64"
+  - dnn: "default"
+    pdu_session_type: "IPV4V6"
+    ipv4_subnet: "10.0.255.0/24"
+    ipv6_prefix: "2001:1:2::/64"