Unset DISPLAY and DBUS_SESSION_BUS_ADDRESS env variables to ensure the test
won't use user's session bus.
This is useful for unit tests that want to verify behaviour when no session
bus is running. It is not necessary to call this if unit test already calls
g_test_dbus_up() before acquiring the session bus.
Unset DISPLAY and DBUS_SESSION_BUS_ADDRESS env variables to ensure the test won't use user's session bus. This is useful for unit tests that want to verify behaviour when no session bus is running. It is not necessary to call this if unit test already calls g_test_dbus_up() before acquiring the session bus.