Failed evacuations leave cinder volumes mapped to destination host

[Matt Rabe]

Description
===========
If a recreate fails after the instance's volumes have their connections initialized on the destination, the connections are not terminated.

Steps to reproduce
==================
During the recreate flow, if after the volumes are attached to the destination something fails, then the volumes are left attached.

To reproduce one could patch manager.py on the destination host and if the compute driver uses the default manager rebuild implementation then force an exception to be raised after the attach_block_devices call in _rebuild_default_impl. Then issue an evacuation of an instance to this host after picking up the patch.

Expected result
===============
Storage cleanup needs to occur, e.g. host mappings on the storage provider for the destination host need to be removed.

Actual result
=============
Host mappings remain on the storage provider.

Environment
===========
1. Exact version of OpenStack you are running. See the following
   Newton

2. Which hypervisor did you use?
   PowerVM (nova-powervm)

2. Which storage type did you use?
   Cinder (storwize)

3. Which networking type did you use?
   Neutron with SEA

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/442105

[Sean Dague (sdague)]

Automatically discovered version newton in description. If this is incorrect, please update the description to include 'nova version: ...'

[OpenStack Infra (hudson-openstack)]

Change abandoned by Lee Yarwood (<email address hidden>) on branch: master
Review: https://review.openstack.org/442105

[OpenStack Infra (hudson-openstack)]

Change abandoned by Lee Yarwood (<email address hidden>) on branch: master
Review: https://review.opendev.org/442105