Find a way to make sure admin user creation is only attempted once in Keycloak

We have this: https://gitlab.archlinux.org/archlinux/infrastructure/-/blob/master/roles/keycloak/tasks/main.yml#L14

I think that used to work but somehow that file it supposedly creates doesn't actually exist and now it tries to create a new admin user every time the role is run.

Try to find a way to make sure that it sees that an admin is already created.