YT-22409 fix PR issues

commit_hash:58c18d7fc242d1b563efc9a1f0196e3835698888

Author: lukyanovx

yt/yt/client/api/query_tracker_client.h

@@ -123,7 +123,7 @@ struct TQueryResult
     NTableClient::TTableSchemaPtr Schema;
     NChunkClient::NProto::TDataStatistics DataStatistics;
     bool IsTruncated;
-    std::optional<NYson::TYsonString> FullResult;
+    NYson::TYsonString FullResult;
 };
 
 void Serialize(const TQueryResult& queryResult, NYson::IYsonConsumer* consumer);

yt/yt/client/api/rpc_proxy/client_impl.cpp

@@ -2358,7 +2358,7 @@ TFuture<TQueryResult> TClient::GetQueryResult(
             .Schema = rsp->has_schema() ? FromProto<NTableClient::TTableSchemaPtr>(rsp->schema()) : nullptr,
             .DataStatistics = FromProto<NChunkClient::NProto::TDataStatistics>(rsp->data_statistics()),
             .IsTruncated = rsp->is_truncated(),
-            .FullResult = rsp->has_full_result() ? std::make_optional(TYsonString(rsp->full_result())) : std::nullopt,
+            .FullResult = rsp->has_full_result() ? TYsonString(rsp->full_result()) : TYsonString(),
         };
     }));
 }