Minor cleanup of utils unit test
Minor cleanup of utils unit test

This patch removes an unnecessary stream seek from one test,
and renames a couple other tests to reflect the refactoring
of the filter_stream function into two separate functions.

Change-Id: Ie6731766028dee2410193ae79ec4c6f985df1a92

openstack/zaqar,openstack/zaqar,openstack/zaqar,openstack/zaqar