sstableloader: Use "client" init to minimize config etc loading.
sstableloader: Use "client" init to minimize config etc loading.

Message-Id: <24b1e1b91946ccf6bb5ff2271897d7f53770fdb4@scylladb.com>

scylladb/scylla-tools-java,scylladb/scylla-tools-java,scylladb/scylla-tools-java,scylladb/scylla-tools-java