test: raft: randomized_nemesis_test: print snapshot details when taking/loading snapshots in `impure_state_machine`
test: raft: randomized_nemesis_test: print snapshot details when taking/loading snapshots in `impure_state_machine`

Useful for debugging.

scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla