The compute API has required cinder API >= 3.44 since Queens [1] for
working with the volume attachments API as part of the wider
volume multi-attach support.
In order to start removing the compatibility code in the compute API
this change adds an upgrade check for the minimum required cinder API
version (3.44).
[1] Ifc01dbf98545104c998ab96f65ff8623a6db0f28
Change-Id: Ic9d1fb364e06e08250c7c5d7d4bdb956cb60e678