Unrescue will not remove rescue disk in ceph when image_type=rbd

[Chung Chih, Hung]

This bug will happen when using libvirt/QEMU and image_type=rbd.

Rescue instance will produce rescue kernel and ramdisk disk in local.
It will also product rescue disk which will saved in ceph by rbd.
When users want to unrescue instance, nova will remove all rescue kernel and ramdisk disk in local.
But rescue disk which was created in rescue step will still exist.
We can using rbd or rados command to show whether objects was still existed in pool or not.
For example:
sudo rbd --pool $POOL_NAME ls | grep .rescue
or
sudo rados --pool $POOL_NAME ls | grep .rescue

Why it will happen?
Because of unrescue action will remove local rescue file and lvm disk but it didn't remove rdb disk.
Therefore we need to add libvirt images_type condition statement which will remove correct type of disk.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/205766

[OpenStack Infra (hudson-openstack)]

Change abandoned by Sean Dague (<email address hidden>) on branch: master
Review: https://review.openstack.org/205766
Reason: This review is > 6 weeks without comment, and failed Jenkins the last time it was checked. We are abandoning this for now. Feel free to reactivate the review by pressing the restore button and leaving a 'recheck' comment to get fresh test results.