**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.
ContextPtr query_context,
    QueryProcessingStage::Enum to_stage,
    const StorageMetadataPtr & metadata_snapshot,
    SelectQueryInfo & query_info) const
{
    if (to_stage >= QueryProcessingStage::Enum::WithMergeableState)
    {
        if (auto projection = getQueryProcessingStageWithAggregateProjection(query_context, metadata_snapshot, query_info))
        {
            query_info.projection = std::move(projection);
            if (query_info.projection->desc->type == ProjectionDescription::Type::Aggregate)
                return QueryProcessingStage::Enum::WithMergeableState;
        }
        else
            query_info.projection = std::nullopt;
    }
    return QueryProcessingStage::Enum::FetchColumns;
}
MergeTreeData & MergeTreeData::checkStructureAndGetMergeTreeData(IStorage & source_table, const StorageMetadataPtr & src_snapshot, const StorageMetadataPtr & my_snapshot) const