YQ-4824 fixed external entity check by database id (#27654)

Author: GrigoriyPA

ydb/core/kqp/federated_query/kqp_federated_query_helpers.cpp

@@ -372,9 +372,11 @@ namespace {
         const TString& structuredTokenJson,
         const TString& path) {
 
-        if (!federatedQuerySetup || !federatedQuerySetup->Driver) {
-            return NThreading::MakeFuture<TGetSchemeEntryResult>(); 
+        if (!federatedQuerySetup || !federatedQuerySetup->Driver || !endpoint || !database) {
+            LOG_NOTICE_S(*NActors::TActivationContext::ActorSystem(), NKikimrServices::KQP_GATEWAY, "Skipped describe for path '" << path << "' in external YDB database '" << database << "' with endpoint '" << endpoint << "'");
+            return NThreading::MakeFuture<TGetSchemeEntryResult>(TGetSchemeEntryResult{.EntryType = NYdb::NScheme::ESchemeEntryType::Table}); 
         }
+
         std::shared_ptr<NYdb::ICredentialsProviderFactory> credentialsProviderFactory = NYql::CreateCredentialsProviderFactoryForStructuredToken(nullptr, structuredTokenJson, false);
         auto driver = federatedQuerySetup->Driver;