**Describe the bug**
For DATABASE ENGINE Atomic (used by Default for all databases from 20.10) 
when try to `DROP TALBE replicatedmergetree table ON CLUSTER ... SYNC`, query failed after `distributed_ddl_task_timeout` seconds
`decrease `database_atomic_delay_before_drop_table_sec=1` and setup `database_atomic_wait_for_drop_and_detach_synchronously=1` for default user profile didn't help

**How to reproduce**
just look to https://gist.github.com/Slach/a7f2946a108883f6b1d5585b1b5b6b0d
```
bash -x ./reproduce.sh
```

* Which ClickHouse server version to use
Latest official docker build

* Non-default settings, if any
```
<yandex>
    <database_atomic_delay_before_drop_table_sec>1</database_atomic_delay_before_drop_table_sec>
    <profile>
        <default>
            <database_atomic_wait_for_drop_and_detach_synchronously>1</database_atomic_wait_for_drop_and_detach_synchronously>
            <distributed_ddl_task_timeout>20</distributed_ddl_task_timeout>
        </default>
    </profile>
</yandex>

```

**Expected behavior**
Successfull DROP TABLE on cluster

**Error message and/or stacktrace**
Code: 159. DB::Exception: Received from localhost:9000. DB::Exception: Watching task /clickhouse/task_queue/ddl/query-0000000001 is executing longer than distributed_ddl_task_timeout (=20) seconds. There are 2 unfinished hosts (0 of them are currently active), they are going to execute the query in background.

**Additional context**
table physically deleted, but Atomic engine doesn't return "finished" flag to Zookeeper `distributed_ddl` queue

```
docker-compose exec clickhouse-0-0-0 clickhouse-client -q "SELECT * FROM system.zookeeper WHERE path='/clickhouse/task_queue/ddl/query-0000000001/finished' FORMAT
Vertical"
```

returns empty result


throw Exception(ErrorCodes::TIMEOUT_EXCEEDED,
                    "Watching task {} is executing longer than distributed_ddl_task_timeout (={}) seconds. "
                    "There are {} unfinished hosts ({} of them are currently active), they are going to execute the query in background",
                    node_path, timeout_seconds, num_unfinished_hosts, num_active_hosts);
            }
            if (num_hosts_finished != 0 || try_number != 0)
            {
                sleepForMilliseconds(std::min<size_t>(1000, 50 * (try_number + 1)));
            }
            
            if (!zookeeper->exists(node_path))
            {
                throw Exception(ErrorCodes::UNFINISHED,
                    "Cannot provide query execution status. The query's node {} has been deleted by the cleaner since it was finished (or its lifetime is expired)",
                    node_path);
            }
            Strings new_hosts = getNewAndUpdate(getChildrenAllowNoNode(zookeeper, fs::path(node_path) / "finished"));
            ++try_number;
            if (new_hosts.empty())
                continue;
            current_active_hosts = getChildrenAllowNoNode(zookeeper, fs::path(node_path) / "active");
            MutableColumns columns = sample.cloneEmptyColumns();
            for (const String & host_id : new_hosts)
            {
                ExecutionStatus status(-1, "Cannot obtain error message");
                {
                    String status_data;
                    if (zookeeper->tryGet(fs::path(node_path) / "finished" / host_id, status_data))
                        status.tryDeserializeText(status_data);
                }