**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.
ErrorCodes::TOO_MANY_PARTS,
            "Too many parts ({}). Merges are processing significantly slower than inserts",
            parts_count_in_partition);
    }
    if (k_inactive < 0 && parts_count_in_partition < settings->parts_to_delay_insert)
        return;
    const ssize_t k_active = ssize_t(parts_count_in_partition) - ssize_t(settings->parts_to_delay_insert);
    size_t max_k;
    size_t k;
    if (k_active > k_inactive)
    {
        max_k = settings->parts_to_throw_insert - settings->parts_to_delay_insert;
        k = k_active + 1;
    }
    else
    {
        max_k = settings->inactive_parts_to_throw_insert - settings->inactive_parts_to_delay_insert;
        k = k_inactive + 1;
    }
    const double delay_milliseconds = ::pow(settings->max_delay_to_insert * 1000, static_cast<double>(k) / max_k);
    ProfileEvents::increment(ProfileEvents::DelayedInserts);
    ProfileEvents::increment(ProfileEvents::DelayedInsertsMilliseconds, delay_milliseconds);
    CurrentMetrics::Increment metric_increment(CurrentMetrics::DelayedInserts);
    LOG_INFO(log, "Delaying inserting block by {} ms. because there are {} parts", delay_milliseconds, parts_count_in_partition);
    if (until)
        until->tryWait(delay_milliseconds);
    else
        std::this_thread::sleep_for(std::chrono::milliseconds(static_cast<size_t>(delay_milliseconds)));
}
MergeTreeData::DataPartPtr MergeTreeData::getActiveContainingPart(