version 21.5.5.12 (official build)

I'm trying to change data type for a column that is used in the TTL expression.
It works well when the table is empty.
When the table is not empty, the mutation fails.
As a result the table ends up in an inconsistent state.

```
create table test
(
InsertionDateTime DateTime,
TTLDays Int32 DEFAULT CAST(365, 'Int32')
)
Engine=MergeTree()
order by tuple()
TTL InsertionDateTime + toIntervalDay(TTLDays);

Ok.

insert into test values (now(), 23);

Ok.

ALTER TABLE test modify column TTLDays Int16 DEFAULT CAST(365, 'Int16');

Code: 341, e.displayText() = DB::Exception: Exception happened during execution of mutation 'mutation_2.txt' with part 'all_1_1_0' reason: 'Code: 10, e.displayText() = DB::Exception: Not found column InsertionDateTime in block. There are only columns: TTLDays (version 21.5.5.12 (official build))'. This error maybe retryable or not. In case of unretryable error, mutation can be killed with KILL MUTATION query (version 21.5.5.12 (official build)) [DB Errorcode=341]

insert into test values (now(), 23);

Ok.

select table, column, type, sum(rows) rows, sum(column_bytes_on_disk) on_disk
from system.parts_columns where column like 'TTLDays'
group by database, table, column, type

table | column  | type  | rows | on_disk
------+---------+-------+------+--------
test  | TTLDays | Int32 |    1 |      86
test  | TTLDays | Int16 |    1 |      84
```
NameSet files_to_skip = collectFilesToSkip(
            source_part,
            mutation_kind == MutationsInterpreter::MutationKind::MUTATE_INDEX_PROJECTION ? Block{} : updated_header,
            indices_to_recalc,
            mrk_extension,
            projections_to_recalc);
        NameToNameVector files_to_rename = collectFilesForRenames(source_part, for_file_renames, mrk_extension);
        if (indices_to_recalc.empty() && projections_to_recalc.empty() && mutation_kind != MutationsInterpreter::MutationKind::MUTATE_OTHER
            && files_to_rename.empty())
        {
            LOG_TRACE(
                log, "Part {} doesn't change up to mutation version {} (optimized)", source_part->name, future_part.part_info.mutation);
            return data.cloneAndLoadDataPartOnSameDisk(source_part, "tmp_clone_", future_part.part_info, metadata_snapshot);
        }
        if (need_remove_expired_values)
            files_to_skip.insert("ttl.txt");
        disk->createDirectories(new_part_tmp_path);
        
        for (auto it = disk->iterateDirectory(source_part->getFullRelativePath()); it->isValid(); it->next())
        {
            if (files_to_skip.count(it->name()))
                continue;
            String destination = new_part_tmp_path;
            String file_name = it->name();
            auto rename_it = std::find_if(files_to_rename.begin(), files_to_rename.end(), [&file_name](const auto & rename_pair) { return rename_pair.first == file_name; });
            if (rename_it != files_to_rename.end())
            {
                if (rename_it->second.empty())
                    continue;
                destination += rename_it->second;