**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))



query_analyzer->aggregates(),
        false,
        settings.max_rows_to_group_by,
        settings.group_by_overflow_mode,
        0,
        0,
        settings.max_bytes_before_external_group_by,
        settings.empty_result_for_aggregation_by_empty_set,
        context->getTemporaryVolume(),
        settings.max_threads,
        settings.min_free_disk_space_for_temporary_data,
        settings.compile_aggregate_expressions,
        settings.min_count_to_compile_aggregate_expression);
    auto transform_params = std::make_shared<AggregatingTransformParams>(params, true);
    QueryPlanStepPtr step;
    if (modificator == Modificator::ROLLUP)
        step = std::make_unique<RollupStep>(query_plan.getCurrentDataStream(), std::move(transform_params));
    else
        step = std::make_unique<CubeStep>(query_plan.getCurrentDataStream(), std::move(transform_params));
    query_plan.addStep(std::move(step));
}
void InterpreterSelectQuery::executeExpression(QueryPlan & query_plan, const ActionsDAGPtr & expression, const std::string & description)
{
    if (!expression)
        return;
    auto expression_step = std::make_unique<ExpressionStep>(query_plan.getCurrentDataStream(), expression);
    expression_step->setStepDescription(description);
    query_plan.addStep(std::move(expression_step));
}
static bool windowDescriptionComparator(const WindowDescription * _left, const WindowDescription * _right)