When installing Debian 13 (Trixie) via network based deployment, the very first reboot after installation ends up in the BIOS menu.

Reason:

- GRUB2 binary from Foreman Proxy is loaded and executed
- GRUB2 binary fetches GRUB configuration from Foreman Proxy
- GRUB2 configuration boots default "Loading GRUB2 from ESP" menu entry, which simply loads GRUB2 configuration file from disk
- GRUB2 configuration of Debian 13 (Trixie) contains the following a line `fwsetup --is-supported` where the parameter `--is-supported` is not understood by the GRUB2 binary from the Foreman proxy (GRUB2 too old)

Fix:

Simply remove `/etc/grub.d/30_uefi-firmware` in the finish template.
This snippet adds a menu entry in GRUB2 to enter the BIOS screen what can be neglected.