rbd driver in cinder does not manage glance images multi-location

rbd driver in cinder does not manage glance images multi-location

Currently, rbd driver in cinder does not manage properly glance images with
multiple locations when creating a volume from image.

With multi-location feature in glance, a image can have multiple rbd URIs
associated, even in different ceph clusters. When rbd driver tries to create a
volume as a CoW clone from the image, it only check the direct_url URI instead
of all available locations for the image.

This patch iterates over both direct_url and locations URIs looking for a
clonable one.

Change-Id: I2d50b8af7f8f772ffa10d968616309d81e6940ec
Closes-Bug: 1454638