hammer.sh: don't do teuthology-nuke anymore.
hammer.sh: don't do teuthology-nuke anymore.

Apparently `hammer.sh` is pretty old. It calls `teuthology-nuke`
expecting the further call to `teuhology` will be able to still
reach the nodes. However, it doesn't seem that anybody is turning
them back these days.

The commit just drops the `teuthology-nuke` call.

Signed-off-by: Radoslaw Zarzynski <d31de3f997a9c1b9030b4b8b5b187b0d81e03886@redhat.com>

dmick/teuthology,ktdreyer/teuthology,ktdreyer/teuthology,SUSE/teuthology,dmick/teuthology,dmick/teuthology,ceph/teuthology,SUSE/teuthology,ceph/teuthology,SUSE/teuthology