Modify security service list test

Since we decoupled ``share:get_all_security_services`` from
``context_is_admin``, we started preventing non-admins to use
the ``all_tenants`` flag for security service listing.

This change enhances one of our tests to ensure that in a
query to list security services using ``all_tenants``,
less-privileged users won't be able to see more security
services than they should.

Related-Bug: #1916102
Change-Id: Idd49e22c8dc534a1fe1e4814f233b079cf14bb72
1 file changed