Add functional test for deleting BFV server with old attach flow
Add functional test for deleting BFV server with old attach flow

When creating a new instance and deleting it before it gets scheduled
with the old attachment flow (reserve_volume), the block device mappings
are not persisted to database which means that the clean up fails
because it tries to lookup attachment_id which cannot be lazy loaded.

This patch adds a (failing) functional test to check for this issue
which will be addressed in a follow-up patch.

Conflicts:
	nova/tests/functional/wsgi/test_servers.py

Related-Bug: #1750666
Change-Id: I294c54e5a22dd6e5b226a4b00e7cd116813f0704
(cherry picked from commit 3120627d9802ceda46c2db387fec8fbc80700338)

vmturbo/nova,vmturbo/nova,vmturbo/nova,vmturbo/nova