**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))



{
            if (required_source_columns.count(column))
                step.addRequiredOutput(column);
        }
        auto names = step.actions()->getNames();
        NameSet name_set(names.begin(), names.end());
        for (const auto & column : sourceColumns())
            if (required_source_columns.count(column.name) == 0)
                name_set.erase(column.name);
        Names required_output(name_set.begin(), name_set.end());
        prewhere_actions = chain.getLastActions();
        prewhere_actions->removeUnusedActions(required_output);
    }
    {
        
        
        
        
        
        
        
        ColumnsWithTypeAndName columns = prewhere_actions->getResultColumns();
        auto required_columns = prewhere_actions->getRequiredColumns();
        NameSet prewhere_input_names;
        NameSet unused_source_columns;
        for (const auto & col : required_columns)
            prewhere_input_names.insert(col.name);
        for (const auto & column : sourceColumns())
        {
            if (prewhere_input_names.count(column.name) == 0)