This change addresses a few inconsistencies in how nova processes
are configured to speak to the placement service.
The initial inspiration was that region_name was not being set in the
[placement] section, despite $REGION_NAME being used when setting
the endpoint in the catalog. That's fixed.
While fixing that two other issues became clear:
* Configuring nova process to use placement should happen in lib/nova
not lib/placement so the function has been moved.
* auth_strategy is not relevant in the [placement] section of a
nova process
The name of the function is maintained, in case there are plugins which
call it, but a comment is added to indicate that other services besides
nova compute (such as the cell conductor) may use the function.
Change-Id: I4a46b6460596e9a445bd90de2d52dbb71fb963df
16a10d7435