lsa: Add use for debug::static_migrators
lsa: Add use for debug::static_migrators

Otherwise GDB complains about it being optimized out, breaking our
debug scritps.

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