mutation_partition: do not add ck to result when not asked to
mutation_partition: do not add ck to result when not asked to

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

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