Add missing stats info to BaremetalNodeState

This is the first of two patches to prepare baremetal for the removal
of capabilities in Nova HostManager.

BaremetalHostManager used to rely on capabilities info to decide which
host state class to use, VM or baremetal. This has been broken since
host capabilities reporting were removed in Nova, resulting in Nova
HostState class always being used.

BaremetalNodeState lacks stats info needed by some filters during
scheduling. This may result in failures like ComputeCapabilitiesFilter
not returning any hosts. This must be fixed before BaremetalNodeState
can be used again.

Change-Id: I63d992371640b2fd33d35eae72201fd41944f8a4
Partial-Bug: #1260265
Fix BaremetalHostManager node detection logic

This is the second patch to prepare baremetal for the removal of
capabilities in Nova HostManager.

BaremetalHostManager used to rely on capabilities info to decide which
host state class to use, VM or baremetal. This has been broken since
host capabilities reporting were removed in Nova, resulting in Nova
HostState class always being used.

This patch fixes the detection logic in BaremetalHostManager to
correctly choose BaremetalHostState class for use with baremetal nodes.
Tests are added to verify that the correct class is used for both vm
and baremetal nodes.

In reality, the new detection logic will not start to deliver the
correct HostState class until the Nova HostManager change that follows
has landed.

Change-Id: I0c2e6d985fb29f35b823cdf9a83fead2fa45082a
Partial-Bug: #1260265
Remove traces of now unused host capabilities from scheduler

This is take two of this patch. This time after preparing Baremetal
and Ironic code to work with the HostManager changes introduced in
this patch.

Host capabilities updates are no longer used by the scheduler. All host
state is instead fetched from the DB. Some left over fields are still
kept by the host manager but contain no data. This change remove the
last traces of host capabilities from the scheduler.

Baremetal/Ironic host managers used to rely on capabilities info to
decide which host state class to use, VM or baremetal. This has been
broken since host capabilities reporting were removed. This change
works in tandem with prior updates to Baremetal/Ironic node detection
logic to fix this problem.

Important: This must not be approved until the Ironic patch in
https://review.openstack.org/97447 has first landed!

Change-Id: Id5f88c0aa1df9152ddb62904b0544801a8bcfd2a
Closes-Bug: #1260265