After the integration with placement [1], we need to configure how
zun-compute is going to work with nova-compute.

* If zun-compute and nova-compute run on the same compute node,
  we need to set 'host_shared_with_nova' as true so that Zun
  will use the resource provider (compute node) created by nova.
  In this mode, containers and VMs could claim allocations against
  the same resource provider.
* If zun-compute runs on a node without nova-compute, no extra
  configuration is needed. By default, each zun-compute will create
  a resource provider in placement to represent the compute node
  it manages.

[1] https://blueprints.launchpad.net/zun/+spec/use-placement-resource-management

Change-Id: I2d85911c4504e541d2994ce3d48e2fbb1090b813