Zanzana: Lazy load cached store info (#96452)

* Lazy load cached store infos

pkg/services/authz/zanzana/server/server_write.go

@@ -13,13 +13,10 @@ func (s *Server) Write(ctx context.Context, req *authzextv1.WriteRequest) (*auth
 	ctx, span := tracer.Start(ctx, "authzServer.Write")
 	defer span.End()
 
-	storeInf, err := s.getNamespaceStore(ctx, req.Namespace)
+	storeInf, err := s.getStoreInfo(ctx, req.Namespace)
 	if err != nil {
 		return nil, err
 	}
-	if storeInf.AuthorizationModelId == "" {
-		return nil, errAuthorizationModelNotInitialized
-	}
 
 	writeTuples := make([]*openfgav1.TupleKey, 0)
 	for _, t := range req.GetWrites().GetTupleKeys() {