Users can see target shards during splits and moves on workers

When connecting to a worker, we only show distributed tables even though the shards are in the same schema. However, we only hide shards that are in the metadata, and not shards that are still under constructions like target shards in a move or split. We should consider hiding those shards as well, because it might be confusing and users might try to drop them. We do no guard against users dropping them.