repair: fix missing default values
repair: fix missing default values

A default value was not set for the "incremental" and "parallelism"
repair parameters, so Scylla can wrongly decide that they have an
unsupported value.

Signed-off-by: Nadav Har'El <625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>

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