21.7.3 throws an exception if `_sample_factor` is used in a query:
```
CREATE TABLE sessions
(
  `user_id` UInt64
)
ENGINE = MergeTree
ORDER BY user_id 
SAMPLE BY user_id;

insert into sessions values(1);

SELECT
    sum(user_id * _sample_factor) 
FROM sessions
SAMPLE 10000000

DB::Exception: Cannot find column `user_id` in source stream (version 21.8.1.7409 (official build))

SELECT
    sum(user_id) 
FROM sessions
SAMPLE 10000000

sum(user_id)
------------
           1
```
No exception on 21.6.5
Pipe & pipe,
    size_t num_output_streams,
    const SortDescription & sort_description,
    MergeTreeData::MergingParams merging_params,
    Names partition_key_columns,
    size_t max_block_size)
{
    const auto & header = pipe.getHeader();
    size_t num_outputs = pipe.numOutputPorts();
    auto get_merging_processor = [&]() -> MergingTransformPtr
    {
        switch (merging_params.mode)
        {
            case MergeTreeData::MergingParams::Ordinary:
            {
                return std::make_shared<MergingSortedTransform>(header, num_outputs,
                           sort_description, max_block_size);
            }
            case MergeTreeData::MergingParams::Collapsing:
                return std::make_shared<CollapsingSortedTransform>(header, num_outputs,
                           sort_description, merging_params.sign_column, true, max_block_size);
            case MergeTreeData::MergingParams::Summing:
                return std::make_shared<SummingSortedTransform>(header, num_outputs,
                           sort_description, merging_params.columns_to_sum, partition_key_columns, max_block_size);
            case MergeTreeData::MergingParams::Aggregating:
                return std::make_shared<AggregatingSortedTransform>(header, num_outputs,
                           sort_description, max_block_size);