tools/scylla-sstable: use fmt::print in --dump-data
tools/scylla-sstable: use fmt::print in --dump-data

The rest of the code is standardizing on fmt::print(), bring the code
for --dump-data in line.

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