range_streamer: Handle everywhere_topology
range_streamer: Handle everywhere_topology

The everywhere_topology returns the number of nodes in the cluster as
RF. This makes only streaming from the node losing the range impossible
since no node is losing the range after bootstrap.

Shortcut it not to use strict source in case the keyspace is
everywhere_topology.

Refs #8503

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla