auth: Remove outdated "TODO"
auth: Remove outdated "TODO"

Authorization never happens at this level of the stack, though it
formally did.

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