fix: return entity_id when multiple idps and mdq are defined in metadata

Author: sebulibah

src/satosa/backends/saml2.py

@@ -208,6 +208,12 @@ def start_logout(self, context, internal_req, internal_authn_resp):
         """
 
         entity_id = self.get_idp_entity_id(context)
+        if entity_id is None:
+            context.state[Context.KEY_FORCE_AUTHN] = get_force_authn(
+                context, self.config, self.sp.config
+            )
+            return self.disco_query(context)
+
         return self.logout_request(context, entity_id, internal_authn_resp)
 
     def disco_query(self, context):