mutation_partition: make apply_reversibly_intrusive_set nongeneric
mutation_partition: make apply_reversibly_intrusive_set nongeneric

apply_reversibly_intrusive_set is used only in one place
and always with rows_type. There's no need for it to be generic.
This will allow changing intrusive set implementation.

Signed-off-by: Piotr Jastrzebski <2c0eb4a25a7cde333ff2d0860cb06051925fd74f@scylladb.com>

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