since nova api 2.40 the os-simple-tenant-usage API supports pagination
and will by default return a number of entities configured internally in
Nova.
This means that when there are many enough projects,
the single call to usage.list() will not return usages for all projects.
This patch effectively copy-pastes the logic to paginate over usage list
results from novaclient/v2/shell.py code.
Change-Id: I1b639fe386b7b7db3223f6965495094b9d51533a
Story: #2005099
Task: #29713
c79de8a90b