lava: update for session-lock-down-no-deny and apparmor-ofono tests

As defined in test-cases/apparmor-session-lockdown-no-deny.yaml this test doesn't apply for fixedfunction images.

The apparmor ofono test can now be run on OSTree images, but not on fixedfunction images where ofono is not installed.

Signed-off-by: Frédéric Danis frederic.danis@collabora.com