db/view/build_progress_virtual_reader: Use correct schema to adjust ck
db/view/build_progress_virtual_reader: Use correct schema to adjust ck

The virtual reader adjusts clustering keys obtained from the
underlying, scylla-specific schema, and potentially sheds the extra
clustering key that's absent from the Cassandra-compatible schema.

This patches ensures we use the correct schema to iterator over the
key.

Signed-off-by: Duarte Nunes <a60e8b7496f7715d71354fe4c06dd24017025bf1@scylladb.com>

avikivity/scylla,avikivity/scylla,duarten/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,scylladb/scylla,duarten/scylla,scylladb/scylla