Upstream will deprecate usage of eventlet of all the WSGI-run
services, including nova-api and nova-metadata-api.
See https://review.openstack.org/#/c/549510/ for more details.
With this change we move nova-metadata to run via httpd wsgi
and therefore uses its own config volume.
Depends-On: Ic65736cb0e95c400a728cd699ecf06c6aecff832
Change-Id: Ic46acdbac280ac648ec5ed9d7af0139126334fe0
Closes-Bug: 1781405