fup: Keep NovaPlacement in the service registry for upgrades
fup: Keep NovaPlacement in the service registry for upgrades

This was removed in I9e3287bcbe9d317f32bf6b468c6ee17f04b6fff9 but needs
to remain until the U cycle to avoid issues when upgrading from Stein.

Change-Id: Ibf022edd29c07122d0f032e56b63f428ed62f85f

openstack/tripleo-heat-templates,openstack/tripleo-heat-templates