When making a GET /allocation_candidates request with the 'limit'
parameter, include all the providers in the same tree as the providers
mentioned in the allocation requests. That is, in a nested situation,
if we limit the allocation requests to 10, we would usually expect
considerably more than 10 providers in provider summaries, to include
any non-contributing providers in the same tree.
Accomplish this by filtering provider summaries on root_provider_uuid
instead of individual provider uuid.
A gabbi test is added which exercises this in a nested situation.
An existing test is updated to reflect the new filtering style. It
does not exercise the nested scenario.
A reno is added indicating the fix.
Change-Id: I136bd7cd89f1bd54f0d1691268545850af234f18
Story: 2005859
Task: 33654