**Describe what's wrong**

Query with rollup using same selected field name as the name of underlying column reports structure mismatch

**Does it reproduce on recent release?**

yes

**How to reproduce**

`21.9.2.17`

```sql
CREATE TABLE test
(
    `d` DateTime,
    `a` LowCardinality(String),
    `b` UInt64
)
ENGINE = MergeTree
PARTITION BY toDate(d)
ORDER BY d;

SELECT *
FROM (
    SELECT
        a,
        max((d, b)).2 AS value
    FROM test
    GROUP BY rollup(a)
)
WHERE a <> '';
```

**Expected behavior**

This used to return an ok result on v21.8

**Error message and/or stacktrace**

> Code: 352. DB::Exception: Block structure mismatch in (columns with identical name must have identical structure) stream: different columns:
> notEquals(a, '') LowCardinality(UInt8) ColumnLowCardinality(size = 0, UInt8(size = 0), ColumnUnique(size = 1, UInt8(size = 1)))
> notEquals(a, '') LowCardinality(UInt8) Const(size = 0, ColumnLowCardinality(size = 1, UInt8(size = 1), ColumnUnique(size = 2, UInt8(size = 2)))). (AMBIGUOUS_COLUMN_NAME) (version 21.9.2.17 (official build))



|| (settings.empty_result_for_aggregation_by_constant_keys_on_empty_set && keys.empty()
                && query_analyzer->hasConstAggregationKeys()),
        context->getTemporaryVolume(),
        settings.max_threads,
        settings.min_free_disk_space_for_temporary_data,
        settings.compile_aggregate_expressions,
        settings.min_count_to_compile_aggregate_expression);
    SortDescription group_by_sort_description;
    if (group_by_info && settings.optimize_aggregation_in_order)
        group_by_sort_description = getSortDescriptionFromGroupBy(getSelectQuery());
    else
        group_by_info = nullptr;
    auto merge_threads = max_streams;
    auto temporary_data_merge_threads = settings.aggregation_memory_efficient_merge_threads
        ? static_cast<size_t>(settings.aggregation_memory_efficient_merge_threads)
        : static_cast<size_t>(settings.max_threads);
    bool storage_has_evenly_distributed_read = storage && storage->hasEvenlyDistributedRead();
    auto aggregating_step = std::make_unique<AggregatingStep>(
        query_plan.getCurrentDataStream(),
        params,
        final,
        settings.max_block_size,
        merge_threads,
        temporary_data_merge_threads,
        storage_has_evenly_distributed_read,
        std::move(group_by_info),
        std::move(group_by_sort_description));
    query_plan.addStep(std::move(aggregating_step));
}
void InterpreterSelectQuery::executeMergeAggregated(QueryPlan & query_plan, bool overflow_row, bool final)