**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 the storage requires some complicated work on destroying,
      * then you have two virtual methods:
      * - flush()
      * - shutdown()
      *
      * @see shutdown()
      * @see flush()
      */
    void flushAndShutdown()
    {
        flush();
        shutdown();
    }
    /** If the table have to do some complicated work when destroying an object - do it in advance.
      * For example, if the table contains any threads for background work - ask them to complete and wait for completion.
      * By default, does nothing.
      * Can be called simultaneously from different threads, even after a call to drop().
      */
    virtual void shutdown() {}
    
    
    virtual void flush() {}