**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 (auto part = outdatePart(part_name,  false))
        dropPartsImpl({part},  false);
    
}
void StorageMergeTree::dropPart(const String & part_name, bool detach, ContextPtr )
{
    if (auto part = outdatePart(part_name,  true))
        dropPartsImpl({part}, detach);
}
void StorageMergeTree::dropPartition(const ASTPtr & partition, bool detach, ContextPtr local_context)
{
    DataPartsVector parts_to_remove;
    
    {
        
        
        auto merge_blocker = stopMergesAndWait();
        String partition_id = getPartitionIDFromQuery(partition, local_context);
        parts_to_remove = getDataPartsVectorInPartition(MergeTreeDataPartState::Committed, partition_id);
        
        removePartsFromWorkingSet(parts_to_remove, true);
    }
    dropPartsImpl(std::move(parts_to_remove), detach);
}
void StorageMergeTree::dropPartsImpl(DataPartsVector && parts_to_remove, bool detach)