Remove unnecessary cinder metadata

Previously all cinder functionality was in a single element and
required "volume: 'true'" to install the cinder-volume service.
Now cinder has been split into multiple elements and you build
an image with the cinder-volume element to achieve the same goal.

This patch removes the "volume: 'true'".

Change-Id: I2ed2e6f7c7db7619aee7ce4ba730f310344e0b0e
Merge "Remove unnecessary cinder metadata"