enhance: [StorageV2] Release record and close reader (#42983)

Related to #39173

This PR
- Close packed reader after sort
- Release arrow.Record preventing memory leakage
- Invoke `pack_reader->Close()` for CloseReader

---------

Signed-off-by: Congqi Xia <congqi.xia@zilliz.com>

internal/core/src/segcore/packed_reader_c.cpp

@@ -138,6 +138,7 @@ CloseReader(CPackedReader c_packed_reader) {
         auto packed_reader =
             static_cast<milvus_storage::PackedRecordBatchReader*>(
                 c_packed_reader);
+        packed_reader->Close();
         delete packed_reader;
         return milvus::SuccessCStatus();
     } catch (std::exception& e) {

internal/datanode/index/task_stats.go

@@ -242,6 +242,7 @@ func (st *statsTask) sort(ctx context.Context) ([]*datapb.FieldBinlog, error) {
 		log.Warn("error creating insert binlog reader", zap.Error(err))
 		return nil, err
 	}
+	defer rr.Close()
 
 	rrs := []storage.RecordReader{rr}
 	numValidRows, err := storage.Sort(st.req.GetBinlogMaxSize(), st.req.GetSchema(), rrs, srw, predicate)

internal/storage/sort.go

@@ -68,6 +68,13 @@ func Sort(batchSize uint64, schema *schemapb.CollectionSchema, rr []RecordReader
 		return 0, nil
 	}
 
+	// release cgo records
+	defer func() {
+		for _, rec := range records {
+			rec.Release()
+		}
+	}()
+
 	pkField, err := typeutil.GetPrimaryFieldSchema(schema)
 	if err != nil {
 		return 0, err