Grab instance for migration before updating usage
Grab instance for migration before updating usage

Updates _update_usage_from_migrations so that it grabs the instance
associated with a migration before updating usage.

Bug 1163622

Change-Id: I64acef912ae71ea5c7fb66e9fcaafe5750c63eaf
(cherry picked from commit a574af21f81e12ea5fd48ad50bd0535d08fcda24)

yrobla/nova,Triv90/Nova,yrobla/nova,Triv90/Nova,yrobla/nova,Triv90/Nova