calamares-nixos-extensions: Remove BIOS boot partition

Calamares doesn't handle this well in combination with EFI
support. The result is that you get an unencrypted ESP and an
encrypted extra partition that isn't even mounted. Since the partition
isn't even needed on BIOS systems for any purpose, just get rid of it.

pkgs/by-name/ca/calamares-nixos-extensions/src/config/modules/partition.conf

@@ -22,17 +22,7 @@ availableFileSystemTypes:
 
 showNotEncryptedBootMessage: false
 
-bios:
-    mountPoint: "/boot"
-    minimumSize: 512MiB
-    recommendedSize: 1GiB
-    label: "BOOT"
-
 partitionLayout:
-    - name: "boot"
-      filesystem: "ext4"
-      mountPoint: "/boot"
-      size: 1GiB
     - name: "root"
       filesystem: "unknown"
       noEncrypt: false