storage_service: don't use potentially stale iterator in log
storage_service: don't use potentially stale iterator in log

Message-Id: <c7c9f176e5769c893350e376f34e6338c0b8808b@scylladb.com>

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