**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.
{
    if (action_type == ActionLocks::PartsMerge ||  action_type == ActionLocks::PartsTTLMerge)
        background_operations_assignee.trigger();
    else if (action_type == ActionLocks::PartsMove)
        background_moves_assignee.trigger();
}
CheckResults StorageMergeTree::checkData(const ASTPtr & query, ContextPtr local_context)
{
    CheckResults results;
    DataPartsVector data_parts;
    if (const auto & check_query = query->as<ASTCheckQuery &>(); check_query.partition)
    {
        String partition_id = getPartitionIDFromQuery(check_query.partition, local_context);
        data_parts = getDataPartsVectorInPartition(MergeTreeDataPartState::Committed, partition_id);
    }
    else
        data_parts = getDataPartsVector();
    for (auto & part : data_parts)
    {
        auto disk = part->volume->getDisk();
        String part_path = part->getFullRelativePath();
        
        String checksums_path = fs::path(part_path) / "checksums.txt";
        String tmp_checksums_path = fs::path(part_path) / "checksums.txt.tmp";
        if (part->isStoredOnDisk() && !disk->exists(checksums_path))
        {
            try
            {
                auto calculated_checksums = checkDataPart(part, false);