clustering_key_filter: always return ranges in ascending order
clustering_key_filter: always return ranges in ascending order

Originally, ranges for reversed queries were in descending order and
ranges for forward queries in ascending order. However,
streamed_mutations require them to always be in ascending order.

Signed-off-by: Paweł Dziepak <e29bb3265626c60caf76d587cabdfcd8b379ef80@scylladb.com>

duarten/scylla,avikivity/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,kjniemi/scylla,scylladb/scylla,raphaelsc/scylla,kjniemi/scylla,kjniemi/scylla,duarten/scylla,avikivity/scylla,raphaelsc/scylla,raphaelsc/scylla,avikivity/scylla