The libtool wrapper scripts lose argv[0] when execing the real binary.
In the CI Docker container, where the build runs as root, this was actually starting a real slapd on the default port, and converting the config as a side-effect.
Outside Docker, running as a non-root user, this slapd just failed to start, and didn't convert the config either.
Using slapd -Tt fixes the issue but also prints a warning from slaptest since the database hasn't been initialized yet.
Dynamic config isn't actually used in this test script, so let's just run slapd off the config file directly.