
**Bug description**
Unlike `cluster()`, `clusterAllReplicas()` does not implement `_shard_num`. 

I would expect
```
SELECT _shard_num
FROM clusterAllReplicas(prod, system.one)
ORDER BY _shard_num ASC
FORMAT PrettyCompactMonoBlock

┌─_shard_num─┐
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
│          0 │
└────────────┘
```
to have an output more useful like
```
SELECT _shard_num
FROM cluster(prod, system.one)
ORDER BY _shard_num ASC
FORMAT PrettyCompactMonoBlock

┌─_shard_num─┐
│          1 │
│          2 │
│          3 │
│          4 │
│          5 │
│          6 │
│          7 │
│          8 │
│          9 │
│         10 │
│         11 │
│         12 │
│         13 │
│         14 │
│         15 │
└────────────┘
```

**Releases where this has been tested**

* v20.3.12.112-stable

**References**

[cluster, clusterAllReplicas documentation](https://clickhouse.tech/docs/en/sql-reference/table-functions/cluster/)

[_shard_num documentation](https://clickhouse.tech/docs/en/engines/table-engines/special/distributed/#virtual-columns)

Addresses shard_local_addresses;
            ConnectionPoolPtrs all_replicas_pools;
            all_replicas_pools.reserve(replica_addresses.size());
            for (const auto & replica : replica_addresses)
            {
                auto replica_pool = std::make_shared<ConnectionPool>(
                    settings.distributed_connections_pool_size,
                    replica.host_name, replica.port,
                    replica.default_database, replica.user, replica.password,
                    replica.cluster, replica.cluster_secret,
                    "server", replica.compression,
                    replica.secure, replica.priority);
                all_replicas_pools.emplace_back(replica_pool);
                if (replica.is_local)
                    shard_local_addresses.push_back(replica);
            }
            ConnectionPoolWithFailoverPtr shard_pool = std::make_shared<ConnectionPoolWithFailover>(
                        all_replicas_pools, settings.load_balancing,
                        settings.distributed_replica_error_half_life.totalSeconds(), settings.distributed_replica_error_cap);
            if (weight)
                slot_to_shard.insert(std::end(slot_to_shard), weight, shards_info.size());
            shards_info.push_back({
                std::move(insert_paths),
                current_shard_num,
                weight,
                std::move(shard_local_addresses),
                std::move(shard_pool),
                std::move(all_replicas_pools),
                internal_replication
            });