**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))



{
    auto expression_before_aggregation = std::make_unique<ExpressionStep>(query_plan.getCurrentDataStream(), expression);
    expression_before_aggregation->setStepDescription("Before GROUP BY");
    query_plan.addStep(std::move(expression_before_aggregation));
    if (options.is_projection_query)
        return;
    const auto & header_before_aggregation = query_plan.getCurrentDataStream().header;
    ColumnNumbers keys;
    for (const auto & key : query_analyzer->aggregationKeys())
        keys.push_back(header_before_aggregation.getPositionByName(key.name));
    AggregateDescriptions aggregates = query_analyzer->aggregates();
    for (auto & descr : aggregates)
        if (descr.arguments.empty())
            for (const auto & name : descr.argument_names)
                descr.arguments.push_back(header_before_aggregation.getPositionByName(name));
    const Settings & settings = context->getSettingsRef();
    Aggregator::Params params(
        header_before_aggregation,
        keys,
        aggregates,
        overflow_row,
        settings.max_rows_to_group_by,
        settings.group_by_overflow_mode,
        settings.group_by_two_level_threshold,
        settings.group_by_two_level_threshold_bytes,
        settings.max_bytes_before_external_group_by,
        settings.empty_result_for_aggregation_by_empty_set