**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.

Aliases & ,
                              const NameSet & ,
                              const std::vector<TableWithColumnNamesAndTypes> & ,
                              const StorageMetadataPtr & metadata_snapshot,
                              const ConstStoragePtr & storage)
{
    SubstituteColumnOptimizer(select_query, metadata_snapshot, storage).perform();
}
bool convertQueryToCNF(ASTSelectQuery * select_query)
{
    if (select_query->where())
    {
        auto cnf_form = TreeCNFConverter::tryConvertToCNF(select_query->where());
        if (!cnf_form)
            return false;
        cnf_form->pushNotInFuntions();
        select_query->refWhere() = TreeCNFConverter::fromCNF(*cnf_form);
        return true;
    }
    return false;
}
void optimizeUsing(const ASTSelectQuery * select_query)