The libtool wrapper scripts lose argv[0] when exec'ing 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.

Outside Docker, running as a non-root user, this slapd would just fail
to start, and wouldn'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.