Tighten our VM check: whether we run in a VM is not enough to do AF_VSOCK. We also need to check if we are run in a container, because if we run in a container inside a VM then we should *not* do the AF_VSOCK stuff, but leave the port free for the VM itself. As discussed here: https://github.com/systemd/systemd/pull/31544#issuecomment-1971455401