adding env to support the udr and udm options

Signed-off-by: ismail <mohammed.ismail@openairinterface.org>

etc/amf.conf

@@ -102,8 +102,8 @@ AMF =
      # STRING, {"yes", "no"}, 
      NF_REGISTRATION = "@NF_REGISTRATION@";  # Set to yes if AMF resgisters to an NRF
      SMF_SELECTION   = "@SMF_SELECTION@";    # Set to yes to enable SMF discovery and selection
-     EXTERNAL_AUSF   = "no";  # Set to yes if AMF works with an external AUSF
-     EXTERNAL_UDM    = "no";  # Set to yes if AMF works with an external UDM
+     EXTERNAL_AUSF   = "@EXTERNAL_AUSF@";  # Set to yes if AMF works with an external AUSF
+     EXTERNAL_UDM    = "@EXTERNAL_UDM@";  # Set to yes if AMF works with an external UDM
      USE_FQDN_DNS    = "@USE_FQDN_DNS@";  # Set to yes if AMF relies on a DNS to resolve NRF/SMF/UDM/AUSF's FQDN
   }