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 
{
public:
    static constexpr auto name = Name::name;
    static FunctionPtr create(ContextPtr) { return std::make_shared<FunctionCutToFirstSignificantSubdomainCustomImpl>(); }
    String getName() const override { return name; }
    size_t getNumberOfArguments() const override { return 2; }
    bool isSuitableForShortCircuitArgumentsExecution(const DataTypesWithConstInfo & ) const override { return true; }
    bool useDefaultImplementationForConstants() const override { return true; }
    ColumnNumbers getArgumentsThatAreAlwaysConstant() const override { return {1}; }
    DataTypePtr getReturnTypeImpl(const ColumnsWithTypeAndName & arguments) const override
    {
        if (!isString(arguments[0].type))
            throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
                "Illegal type {} of first argument of function {}. Must be String.",
                arguments[0].type->getName(), getName());
        if (!isString(arguments[1].type))
            throw Exception(ErrorCodes::ILLEGAL_TYPE_OF_ARGUMENT,
                "Illegal type {} of second argument (TLD_list_name) of function {}. Must be String/FixedString.",
                arguments[1].type->getName(), getName());
        const auto * column = arguments[1].column.get();
        if (!column || !checkAndGetColumnConstStringOrFixedString(column))
            throw Exception(ErrorCodes::ILLEGAL_COLUMN,
                "The second argument of function {} should be a constant string with the name of the custom TLD",
                getName());
        return arguments[0].type;
    }
    ColumnPtr executeImpl(const ColumnsWithTypeAndName & arguments, const DataTypePtr & , size_t ) const override