Fix tests on LimeSurvey LTS

[p-gw]

The CI tests for LimeSurvey LTS need to be fixed.
For this the API must be exposed before the first login, otherwise get_session_key will throw an error.

Meanwhile the tests can be run manually by

1. building the docker container

docker compose -f test/docker-compose.yml -f test/docker-compose.lts.yml up -d --build

2. logging into LimeSurvey via the web browser
3. Running the Julia tests