In order to support cross project request_id tracking, we need to be
on oslo.middleware for request_id. This makes that change now that
oslo middleware can support compat headers.
api-ref is not updated yet because x-compute-request-id was apparently
never documented there, and the timing on landing this is narrow
because the moment a requirements update happens we'll have this new
behavior.
Part of bp:oslo-middleware-request-id
Change-Id: I4d9f91b01de12cd0a676fc649953f98473b6b416