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 
#pragma once
#include <base/find_symbols.h>
#include "domain.h"
#include "tldLookup.h"
namespace DB
{
struct FirstSignificantSubdomainDefaultLookup
{
    bool operator()(const char *src, size_t len) const
    {
        return tldLookup::isValid(src, len);
    }
};
template <bool without_www>
struct ExtractFirstSignificantSubdomain
{
    static size_t getReserveLengthForElement() { return 10; }
    static void execute(const Pos data, const size_t size, Pos & res_data, size_t & res_size, Pos * out_domain_end = nullptr)
    {
        FirstSignificantSubdomainDefaultLookup loookup;
        return execute(loookup, data, size, res_data, res_size, out_domain_end);
    }
    template <class Lookup>
    static void execute(const Lookup & lookup, const Pos data, const size_t size, Pos & res_data, size_t & res_size, Pos * out_domain_end = nullptr)