sdcm.nemesis: Reorganize nemesis disruption method placement
sdcm.nemesis: Reorganize nemesis disruption method placement

Put all disruption methods next to each other, so it's easier
to pinpoint them. Also, rename the kill scylla daemon method,
as it's an auxiliary, not a full fledged disruption function.

Signed-off-by: Lucas Meneghel Rodrigues <8ad3460456640ab580599f5440c5a8d925a620b9@scylladb.com>

scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,amoskong/scylla-cluster-tests,amoskong/scylla-cluster-tests,scylladb/scylla-cluster-tests,amoskong/scylla-cluster-tests,amoskong/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-cluster-tests,scylladb/scylla-longevity-tests,amoskong/scylla-cluster-tests,scylladb/scylla-longevity-tests,scylladb/scylla-longevity-tests