Execute cluster query when cluster is defined only on tinitiator

[ianton-ru]

Query like

SELECT * FROM iceberg(...) SETTINGS object_storage_cluster='swarm'

starts on initiator, later reading is executed on nodes of swarm cluster.
And nodes does not required information about swarm cluster.
Now if cluster is defined only on initiator, swarm nodes return error

DB::Exception: Requested cluster 'swarm' not found. (CLUSTER_DOESNT_EXIST)

It is possible to skip this check on swarm nodes.