**Describe the situation**
multiIf works 10 times slower than If with single condition.

**How to reproduce**
ClickHouse version 21.10

```

SELECT count()
FROM numbers_mt(1000000000)
WHERE NOT ignore(multiIf(number = 0, NULL, toNullable(number)))

┌────count()─┐
│ 1000000000 │
└────────────┘

1 rows in set. Elapsed: 10.267 sec. Processed 1.00 billion rows, 8.00 GB (97.41 million rows/s., 779.25 MB/s.)

SELECT count()
FROM numbers_mt(1000000000)
WHERE NOT ignore(If(number = 0, NULL, toNullable(number)))

┌────count()─┐
│ 1000000000 │
└────────────┘

1 rows in set. Elapsed: 1.010 sec. Processed 1.00 billion rows, 8.00 GB (990.63 million rows/s., 7.93 GB/s.)
```

**Expected performance**
The same performance for multiIf and if.

auto * order_by_element = order_by->children[i]->as<ASTOrderByElement>();
        auto & ast_func = order_by_element->children[0];
        if (!ast_func->as<ASTFunction>())
            continue;
        if (i >= sorting_key_columns.size() || ast_func->getColumnName() != sorting_key_columns[i])
            is_sorting_key_prefix = false;
        
        
        if (is_sorting_key_prefix)
            continue;
        MonotonicityCheckVisitor::Data data{tables_with_columns, context, group_by_hashes};
        MonotonicityCheckVisitor(data).visit(ast_func);
        if (!data.isRejected())
        {
            ast_func = data.identifier->clone();
            ast_func->setAlias("");
            if (!data.monotonicity.is_positive)
                order_by_element->direction *= -1;
        }
    }
}
void optimizeRedundantFunctionsInOrderBy(const ASTSelectQuery * select_query, ContextPtr context)
{
    const auto & order_by = select_query->orderBy();
    if (!order_by)
        return;
    for (const auto & child : order_by->children)
    {
        auto * order_by_element = child->as<ASTOrderByElement>();
        if (!order_by_element || order_by_element->children.empty())