This fixes a regression in Ocata where we were always
decrementing quota usage during instance delete even
if we failed to delete the instance. Now the reservation
is properly committed after the instance is destroyed.
The related functional test is updated to show this working
correctly now.
Conflicts:
nova/compute/api.py
nova/tests/unit/compute/test_compute_api.py
NOTE(mriedem): The conflict is due to not having change
edf51119fa in stable/ocata.
Change-Id: I5200e72c195e12b5a069cbae3f209492ed569fb4
Closes-Bug: #1678326
(cherry picked from commit 5c1af55cbe)