Extend the test to add explicit tests for:
- Query with "visibleto:self".
- Query with "visibleto:username" which should return the same results
as the existing test with "visibleto:accountid".
- Bad request when using "visibleto:" with a non-existent user.
Also refactor the test to explicitly create the second test user
rather than relying on the implicit creation via authentication.
Change-Id: I1a870fedf5f0c8b6656583f3d99b66bc35dbfd75
e8207d53c7