**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.
size_t clearOldTemporaryDirectories(const MergeTreeDataMergerMutator & merger_mutator, size_t custom_directories_lifetime_seconds);
    size_t clearEmptyParts();
    
    
    void dropAllData();
    
    void dropIfEmpty();
    
    
    
    void rename(const String & new_table_path, const StorageID & new_table_id) override;
    
    
    
    
    
    void checkAlterIsPossible(const AlterCommands & commands, ContextPtr context) const override;
    
    
    void checkMutationIsPossible(const MutationCommands & commands, const Settings & settings) const override;
    
    void checkAlterPartitionIsPossible(const PartitionCommands & commands, const StorageMetadataPtr & metadata_snapshot, const Settings & settings) const override;
    
    void changeSettings(
        const ASTPtr & new_settings,
        AlterLockHolder & table_lock_holder);
    
    void reportBrokenPart(const String & name) const