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
Merge "Remove traces of now unused host capabilities from scheduler"