spacemanager: Remove dead code and other minor cleanup

All identified by IntelliJ.

Target: master
Require-notes: no
Require-book: no
Acked-by: Dmitry Litvintsev <litvinse@fnal.gov>
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: http://rb.dcache.org/r/6373/