tests: always use the right vtable wrapper calls
Prompted by https://github.com/systemd/systemd/pull/10836#discussion_r234598868
(cherry picked from commit bd7989a3d90e5d97e09f1eef33d09b2469a79f4d)
Related: #1737283
patch_name: 0381-tests-always-use-the-right-vtable-wrapper-calls.patch
present_in_specfile: true
location_in_specfile: 381
squash_commits: true