No admin with remote_user_guard

[JC5]

Discussed in https://github.com/orgs/firefly-iii/discussions/6145

^{Originally posted by derfloDev June 8, 2022}
Hi, im running FireFlyII with docker-compose and AUTHENTICATION_GUARD=remote_user_guard.
My Authentication Guard is Authelia.
Every thing is working fine so far. I can login an do stuff.
But how do i access the admin Page.
Or how do i tell FireFly which user is the Admin when using remote_user_guard?

First user won't be made admin if it's created through remote user guard.