Used Ansible vars are now flat and not part of a dict. The settings
itself have not changed besides now being prefixed with `podman_`
instead of referencing the dict object via `podman.`.

The firewalld workaround is removed as i am only using netavark as the
network backend for quite some time and the firewalld issue is fixed for
it [1].

Additionally the `default.yml` tasks are removed as i'm not really using
and therefore not updating those. They probably would not have worked
anyway.

[1] https://blog.podman.io/2023/11/new-netavark-firewalld-reload-service/