This follows a change made to devstack-gate in commit 841ebc3 to allow
tempest to succeed even if it happens to run several volume tests in
parallel. Right now it's possible for a tempest-full test (run without
devstack-gate) to fail with an "Insufficient free virtual space" error in
the cinder-scheduler log.
Suggested by: Clark Boylan <clark.boylan@gmail.com>
Closes-Bug: 1743597
Change-Id: I16ccb9976d1bc7c9f56a6a4d73e35042a5867ef9
6bcd8cad16