improvement(cluster.py): update 'create_swap_file'
improvement(cluster.py): update 'create_swap_file'

By removing 'loader' word from log messages because this method
is used not only on 'loader' nodes, but also on 'monitor' ones.

scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests