If you check debian/tests/systemd-service-test.sh [0], the interface in use by the config file is decided at runtime.
What autopkgtest tests are you running? This seem like an ubuntu specific issue. All tests in debian are going fine, both in unstable and in testing [1]. This Debian bug may result in the package being removed from Debian testing for no actual reason. Closing this bug now as it seems totally bogus. [0] https://salsa.debian.org/pkg-suricata-team/pkg-suricata/blob/master/debian/tests/systemd-service-test.sh [1] https://ci.debian.net/packages/s/suricata/
