Tegile tests: Change volume size to int
Tegile tests: Change volume size to int

Defining volume size as a string is not correct, and
causes huge memory consumption when multiplied by
units.Gi in the driver.

Change-Id: Ib4cf13629b70dc1c517e4c12f29c62bb9c75adbf
Closes-Bug: #1535464

Nexenta/cinder,NetApp/cinder,NetApp/cinder,Datera/cinder,mahak/cinder,phenoxim/cinder,eharney/cinder,openstack/cinder,dims/cinder,phenoxim/cinder,j-griffith/cinder,ge0rgi/cinder,Hybrid-Cloud/cinder,j-griffith/cinder,mahak/cinder,openstack/cinder,dims/cinder,Datera/cinder,cloudbase/cinder,Hybrid-Cloud/cinder,eharney/cinder,bswartz/cinder,cloudbase/cinder,Nexenta/cinder,bswartz/cinder