wait_for_cluster_down also watches security groups.
wait_for_cluster_down also watches security groups.

Not doing this was regularly preventing destroy from finishing.

mrtyler/gpii-terraform,mrtyler/gpii-infra,mrtyler/gpii-infra,mrtyler/gpii-terraform,mrtyler/gpii-terraform,mrtyler/gpii-infra,mrtyler/gpii-infra