fix remaining nfs backup unit test memory issue

[Tom Barron]

We need to fix another place in the nfs backup unit tests where the configured file size was larger than the chunk size in the corresponding Swift backup tests. I missed this one in https://review.openstack.org/#/c/165394 and even though code with that fix ran fine in a bare 1GB VM, there are still memory issues when run in CI with a VM of that size.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/188577

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/188577
Committed: https://git.openstack.org/cgit/openstack/cinder/commit/?id=1c1d16e77fe8e57dbf9995dcf042bb6aa2b77309
Submitter: Jenkins
Branch: master

commit 1c1d16e77fe8e57dbf9995dcf042bb6aa2b77309
Author: Tom Barron <email address hidden>
Date: Thu Mar 19 19:10:54 2015 -0400

    Fix remaining memory issues with nfs backup unit tests

    Here we fix another place in the nfs backup unit tests where
    the configured file size was larger than the chunk size in
    the corresponding Swift backup tests. I missed this one in

       https://review.openstack.org/#/c/165394

    and even though code with that fix ran fine in a bare 1GB VM,
    there are still memory issues when run in CI with a VM of that
    size.

    Closes-Bug: 1452811
    Change-Id: I20dcfb657699e1b415ae2e36ec63f8c6b0049285