**How to reproduce**
Clickhouse server 20.13.1.5273
```
CREATE TABLE default.test
(
`key` UInt32,
`ts` DateTime CODEC(DoubleDelta, LZ4),
`db_time` DateTime DEFAULT now() COMMENT 'spout-ignore' CODEC(DoubleDelta, LZ4)
)
ENGINE = MergeTree
PARTITION BY toStartOfTenMinutes(db_time)
ORDER BY (key, ts)
TTL db_time + toIntervalHour(3)
SETTINGS index_granularity = 8192, merge_with_ttl_timeout = 3600, min_rows_for_compact_part = 1000000, min_bytes_for_compact_part = 200000000, in_memory_parts_enable_wal = 0;


INSERT INTO test(key, ts) SELECT number % 1000, now() + intDiv(number,1000) FROM numbers(500);

SELECT * FROM test;
500 rows in set. Elapsed: 0.003 sec.

DETACH TABLE test;

ATTACH TABLE test;

SELECT * FROM test;

0 rows in set. Elapsed: 0.002 sec.
```

**Expected behavior**
Clickhouse would flush parts on disk.
const String & backup_name,
    ContextPtr local_context,
    TableLockHolder &)
{
    return unfreezePartitionsByMatcher([] (const String &) { return true; }, backup_name, local_context);
}
PartitionCommandsResultInfo MergeTreeData::unfreezePartitionsByMatcher(MatcherFn matcher, const String & backup_name, ContextPtr)
{
    auto backup_path = fs::path("shadow") / escapeForFileName(backup_name) / relative_data_path;
    LOG_DEBUG(log, "Unfreezing parts by path {}", backup_path.generic_string());
    PartitionCommandsResultInfo result;
    for (const auto & disk : getStoragePolicy()->getDisks())
    {
        if (!disk->exists(backup_path))
            continue;
        for (auto it = disk->iterateDirectory(backup_path); it->isValid(); it->next())
        {
            const auto & partition_directory = it->name();
            /
            auto found = partition_directory.find('_');
            if (found == std::string::npos)
                continue;
            auto partition_id = partition_directory.substr(0, found);