**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))



* 2) the disambiguation mechanism in SyntaxAnalyzer, that, among
             *    other things, creates unique aliases for columns with same
             *    names from different tables, is applied before these temporary
             *    columns are created by ExpressionAnalyzer.
             * Similar problems should also manifest for function columns, which
             * are likewise created at a later stage by EA.
             * In general, we need to have explicit separation between display
             * names and identifiers for columns. This code is a workaround for
             * a particular subclass of problems, and not a proper solution.
             */
            if (const auto * as_literal = ast->as<ASTLiteral>())
            {
                source_name = as_literal->unique_column_name;
                assert(!source_name.empty());
            }
            result_columns.emplace_back(source_name, result_name);
            step.addRequiredOutput(result_columns.back().second);
        }
    }
    auto actions = chain.getLastActions();
    actions->project(result_columns);
    return actions;
}
void ExpressionAnalyzer::appendExpression(ExpressionActionsChain & chain, const ASTPtr & expr, bool only_types)
{
    ExpressionActionsChain::Step & step = chain.lastStep(sourceColumns());
    getRootActions(expr, only_types, step.actions());
    step.addRequiredOutput(expr->getColumnName());
}
ActionsDAGPtr ExpressionAnalyzer::getActionsDAG(bool add_aliases, bool project_result)