For [the rule in the list](https://github.com/ClickHouse/ClickHouse/blob/82fc7375dd3ac4faae6c3b0db9f3a28fb2802d05/tests/config/top_level_domains/public_suffix_list.dat#L6430) `*.sch.uk` 

and domain like `www.something.sheffield.sch.uk`  the correct / expected result is `sheffield.sch.uk`

Example with python (correct)

```
-- pip install publicsuffix2
-- python3
>>> from publicsuffix2 import get_public_suffix
>>> get_public_suffix('www.something.sheffield.sch.uk')
'something.sheffield.sch.uk'
```

Same from clickhouse:
```
SELECT cutToFirstSignificantSubdomain('www.something.sheffield.sch.uk')

Query id: 9661461f-a393-43ea-97a1-47c0a8850515

┌─cutToFirstSignificantSubdomain('www.something.sheffield.sch.uk')─┐
│ sch.uk                                                           │
└──────────────────────────────────────────────────────────────────┘
```

/cc @azat 
{
        res_data = data;
        res_size = 0;
        Pos tmp;
        size_t domain_length;
        ExtractDomain<without_www>::execute(data, size, tmp, domain_length);
        if (domain_length == 0)
            return;
        if (out_domain_end)
            *out_domain_end = tmp + domain_length;
        
        if (tmp[domain_length - 1] == '.')
            --domain_length;
        res_data = tmp;
        res_size = domain_length;
        const auto * begin = tmp;
        const auto * end = begin + domain_length;
        const char * last_2_periods[2]{};
        const char * prev = begin - 1;
        const auto * pos = find_first_symbols<'.'>(begin, end);