**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.
{
    return getContext()->getMergeList().getMergesWithTTLCount();
}
void MergeTreeData::addPartContributionToDataVolume(const DataPartPtr & part)
{
    increaseDataVolume(part->getBytesOnDisk(), part->rows_count, 1);
}
void MergeTreeData::removePartContributionToDataVolume(const DataPartPtr & part)
{
    decreaseDataVolume(part->getBytesOnDisk(), part->rows_count, 1);
}
void MergeTreeData::increaseDataVolume(size_t bytes, size_t rows, size_t parts)
{
    total_active_size_bytes.fetch_add(bytes, std::memory_order_acq_rel);
    total_active_size_rows.fetch_add(rows, std::memory_order_acq_rel);
    total_active_size_parts.fetch_add(parts, std::memory_order_acq_rel);
}
void MergeTreeData::decreaseDataVolume(size_t bytes, size_t rows, size_t parts)
{
    total_active_size_bytes.fetch_sub(bytes, std::memory_order_acq_rel);
    total_active_size_rows.fetch_sub(rows, std::memory_order_acq_rel);
    total_active_size_parts.fetch_sub(parts, std::memory_order_acq_rel);
}
void MergeTreeData::setDataVolume(size_t bytes, size_t rows, size_t parts)