modules/openstack/nodes/ignition: Remove deprecated sshd option
modules/openstack/nodes/ignition: Remove deprecated sshd option

Recent versions of sshd already set `UsePrivilegeSeparation sandbox`
by default, and this option is deprecated.

squat/tectonic-installer,lander2k2/tectonic-installer,kyoto/tectonic-installer,kyoto/tectonic-installer,squat/tectonic-installer,kalmog/tectonic-installer,cpanato/tectonic-installer,cpanato/tectonic-installer,kalmog/tectonic-installer,kyoto/tectonic-installer,lander2k2/tectonic-installer,lander2k2/tectonic-installer,cpanato/tectonic-installer,lander2k2/tectonic-installer,squat/tectonic-installer,derekhiggins/installer,kalmog/tectonic-installer,cpanato/tectonic-installer,squat/tectonic-installer,kyoto/tectonic-installer,derekhiggins/installer,kyoto/tectonic-installer