Rename some variables

roles/matrix-synapse/templates/ext/mautrix-whatsapp/config.yaml.j2

@@ -1,9 +1,9 @@
 # Homeserver details.
 homeserver:
   # The address that this appservice can use to connect to the homeserver.
-  address: https://{{ hostname_matrix }}
+  address: https://{{ matrix_server_fqn_matrix }}
   # The domain of the homeserver (for MXIDs, etc).
-  domain: {{ hostname_identity }}
+  domain: {{ matrix_domain }}
 
 # Application service host/registration related details.
 # Changing these values requires regeneration of the registration.
@@ -67,7 +67,7 @@ bridge:
   #   domain - All users on that homeserver
   #     mxid - Specific user
   permissions:
-    '{{ hostname_identity }}': user
+    '{{ matrix_domain }}': user
 
 # Logging config.
 logging: