CinderFixture: Return a driver_type of `fake` within connection_info
CinderFixture: Return a driver_type of `fake` within connection_info

Previously the attachment info returned by the fixture would incorrectly
list the driver_type outside of the connection_info dict [1][2]. This
changes moves it within the connection_info dict and updates the type to
`fake` for use by the libvirt driver that provides a compatible volume
driver [3] for use in our functional tests.

[1] https://docs.openstack.org/api-ref/block-storage/v3/index.html?expanded=create-attachment-detail#id407
[2] https://docs.openstack.org/api-ref/block-storage/v3/index.html?expanded=update-an-attachment-detail#id411
[3] https://github.com/openstack/nova/blob/2c3ff1004e8812da0bc4e5502762e6b9a7650846/nova/virt/libvirt/volume/volume.py#L171-L184

Change-Id: I73ff0a7508d9f8f6f3d498be13f6f7c505b05e5c

mahak/nova,klmitch/nova,openstack/nova,mahak/nova,klmitch/nova,klmitch/nova,openstack/nova,openstack/nova,klmitch/nova,mahak/nova