Ensure deleted instances' status is always DELETED

Currently when deleting failed instances that were never assigned a
host, their vm_state is left in 'error' instead of 'deleted'. This is a
problem when invoking the Index Instances REST API with a Changes-Since
query parameter since that API returns both deleted and non-deleted
instances, but currently the failed deleted instances are incorrectly
marked as status:ERROR instead of status:DELETED.

This patch modifies the server ViewBuilder to ensure the status is
correctly set.

Change-Id: I614714676bab4986564b236d74f2c0d77400e48c
Closes-bug: #1243301
Merge "Ensure deleted instances' status is always DELETED"