storage_service: Add more debug info in decommission
storage_service: Add more debug info in decommission

It is useful to debug decommission issue.

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