Fix Buster incompatibilities

- fix locale kernel parameter for installation
- use Buster ISO and checksum and switch to AMD64 architecture
- increase memory of VirtualBox VM to 1 GB to allow graphical installer
- avoid CD questions by pre-seeding apt-setup/cdrom
- uninstall gcc-8 instead of gcc-4.8 in scripts/cleanup.sh
- modify hd-media initrd.gz by adding fdisk udeb content needed by the
  babelbox partition deletion script

debian-babelbox.json

@@ -5,10 +5,8 @@
       "<esc><wait>",
       "install <wait>",
       "preseed/url=http://{{ .HTTPIP }}:{{ .HTTPPort }}/preseed.cfg ",
-      "debian-installer=en_US <wait>",
+      "debian-installer/locale=en_US <wait>",
       "auto <wait>",
-      "locale=en_US <wait>",
-      "kbd-chooser/method=de <wait>",
       "netcfg/get_hostname={{ .Name }} <wait>",
       "netcfg/get_domain=demo.local <wait>",
       "fb=false <wait>",
@@ -19,22 +17,22 @@
       "<enter><wait>"
     ],
     "disk_size": 10240,
-    "guest_os_type": "Debian",
+    "guest_os_type": "Debian_64",
     "hard_drive_interface": "sata",
     "headless": false,
     "http_directory": "http",
-    "iso_checksum": "f270d1ffa0f9472464bfc0fffa7ac3ddc89abb5786eb02454f26e49f143b01d6",
+    "iso_checksum": "6a901b5abe43d88b39d627e1339d15507cc38f980036b928f835e0f0e957d3d8",
     "iso_checksum_type": "sha256",
-    "iso_url": "http://cdimage.debian.org/debian-cd/current/i386/iso-cd/debian-8.3.0-i386-netinst.iso",
+    "iso_url": "https://cdimage.debian.org/debian-cd/current/amd64/iso-cd/debian-10.3.0-amd64-netinst.iso",
     "shutdown_command": "sudo /sbin/halt -p",
     "ssh_username": "demo",
     "ssh_password": "babelbox",
     "ssh_port": "22",
     "ssh_wait_timeout": "1800s",
     "type": "virtualbox-iso",
-    "vm_name": "babelbox-jessie",
+    "vm_name": "babelbox-buster",
     "vboxmanage": [
-      ["modifyvm", "{{.Name}}", "--memory", "512"],
+      ["modifyvm", "{{.Name}}", "--memory", "1024"],
       ["modifyvm", "{{.Name}}", "--cpus", "1"]
     ],
     "output_directory": "babelbox"