[fix](block) fix be core while mutable block merge may cause different row size between columns in origin block (#27943)

be/src/vec/exec/vtable_function_node.cpp

@@ -218,7 +218,7 @@ Status VTableFunctionNode::_get_expanded_block(RuntimeState* state, Block* outpu
     for (auto index : _useless_slot_indexs) {
         columns[index]->insert_many_defaults(row_size - columns[index]->size());
     }
-
+    output_block->set_columns(std::move(columns));
     // 3. eval conjuncts
     RETURN_IF_ERROR(VExprContext::filter_block(_conjuncts, output_block, output_block->columns()));