fix stream lookup bytes calculation (ydb-platform#12026) (ydb-platform#12101)

Author: gridnevvvit

ydb/core/kqp/runtime/kqp_stream_lookup_worker.cpp

@@ -377,9 +377,7 @@ class TKqpLookupRows : public TKqpStreamLookupWorker {
                     }
                 }
 
-                storageRowSize = std::max(storageRowSize, (i64)8);
-
-                if (rowsInBatch && storageRowSize > freeSpace - (i64)resultStats.ResultBytesCount) {
+                if (rowsInBatch && rowSize > freeSpace - (i64)resultStats.ResultBytesCount) {
                     row.DeleteUnreferenced();
                     sizeLimitExceeded = true;
                     break;
@@ -388,6 +386,8 @@ class TKqpLookupRows : public TKqpStreamLookupWorker {
                 batch.push_back(std::move(row));
                 ++rowsInBatch;
 
+                storageRowSize = std::max(storageRowSize, (i64)8);
+
                 resultStats.ReadRowsCount += 1;
                 resultStats.ReadBytesCount += storageRowSize;
                 resultStats.ResultRowsCount += 1;