Nova is Deprecating Hypervisor API Endpoints

As reported on https://bugs.launchpad.net/horizon/+bug/1202965, the data brought by the responses from the Nova hypervisor API endpoint contain inconsistencies between the data it provides and the names of the response fields.

This causes Horizon to display incongruent information on the hypervisor overview view, as the field for vCPUs used (vcpus_used) is really providing the total number dedicated and shared CPUs used while the field for total vCPUs (vcpus) provides information only about shared CPUs. This last field also doesn't account for the configured cpu_allocation_ration.

This results on Horizon displaying, for example, uses of 5 out of 4 vCPUs, if an hypervisor is overcommitting cpus, or even uses of 4 out of 0 vCPUs, if all CPUs are configured as dedicated.

This is troublesome as Nova is, practically, deprecating the Hypervisor API endpoints, see this accepted proposal that REMOVES the fields used by horizon on the latest version of the API: https://review.opendev.org/c/openstack/nova/+/764040/. A fix to the contents of its response should not be expected as a solution.

A possible solution might be transitioning to the Placement API instead, which appears to provide more consistent data and is Being used in Skyline.