Shouldn't this be ComputeSchedulerHints, NovaComputeSchedulerHints is the deprecated option. https://access.redhat.com/documentation/en-us/red_hat_openstack_platform/13/html/advanced_overcloud_customization/sect-controlling_node_placement#annotations:3483372c-ea1b-414e-ad74-c86b43383661
This appears to be rectified froma previous BZ.