**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 (shutdown_called)
        return;
    shutdown_called = true;
    
    {
        std::lock_guard lock(mutation_wait_mutex);
        mutation_wait_event.notify_all();
    }
    merger_mutator.merges_blocker.cancelForever();
    parts_mover.moves_blocker.cancelForever();
    background_operations_assignee.finish();
    background_moves_assignee.finish();
    try
    {
        
        
        
        
        
        clearOldPartsFromFilesystem(true);
    }
    catch (...)
    {
        
        
        tryLogCurrentException(log);
    }
}
StorageMergeTree::~StorageMergeTree()