This code should not read Executor internals:
https://github.com/openstack/nova/blob/7927ab4205b6d749e92b88073e5f000b2e5abc21/nova/utils.py#L1435-L1452

This code should not depend on the locking an internal Executor lock: https://github.com/openstack/nova/blob/7927ab4205b6d749e92b88073e5f000b2e5abc21/nova/utils.py#L590-L599

Revisit utilization statistics gathering, and wait time statistics gathering work in https://review.opendev.org/c/openstack/nova/+/952666

Acceptance criteria:

• futurist lib has enhanced Executor statistics available
• nova uses the above enhanced interface instead of its own hacking code.