gdb: Drop code related to LSA zones
gdb: Drop code related to LSA zones

LSA zones have been removed.

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