[Bug](load) block call clear_column_data may have ref not equal 1 (#12350)

be/src/vec/core/block.cpp

@@ -587,9 +587,7 @@ void Block::clear_column_data(int column_size) noexcept {
         }
     }
     for (auto& d : data) {
-        if (UNLIKELY(d.column->use_count() != 1)) {
-            LOG(WARNING) << "Ref count of column is " << d.column->use_count();
-        }
+        DCHECK(d.column->use_count() == 1);
         (*std::move(d.column)).assume_mutable()->clear();
     }
 }

be/src/vec/exec/vbroker_scan_node.cpp

@@ -262,7 +262,7 @@ Status VBrokerScanNode::scanner_scan(const TBrokerScanRange& scan_range, Scanner
             return Status::Cancelled("Cancelled");
         }
         // Queue size Must be smaller than _max_buffered_batches
-        _block_queue.push_back(block);
+        _block_queue.push_back(std::move(block));
 
         // Notify reader to process
         _queue_reader_cond.notify_one();