Require a tenant aggregate affinity in Placement for successful scheduling

This setting, when limit_tenants_to_placement_aggregate=True, will control whether or not a tenant with no aggregate affinity will be allowed to schedule to any available node.

If aggregates are used to limit some tenants but not all, then this should be False.

If all tenants should be confined via aggregate, then this should be True to prevent them from receiving unrestricted scheduling to any available node.

See also the limit_tenants_to_placement_aggregate option.