batchlog_manager: Rename logger
batchlog_manager: Rename logger

* More useful/referrable on command line (--log*)
* Matches class name (though not origin)

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