DLPX-95602 X11 console Keymaps broken

[tonynguien]

Problem

To update keymapping, /usr/bin/delphix-startup-screen uses sudo localectl set-x11-keymap which is no longer the supported mechanism in Ubuntu 24.04 release. Below shows the error when running the command

delphix@localhost:~$ sudo localectl set-x11-keymap us
Setting X11 and console keymaps is not supported in Debian.

Solution

Set the keyboard layout by editing /etc/default/keyboard and applying it with setupcon. This mechanism avoids localectl set-x11-keymap (which is disabled on Debian/Ubuntu builds).

Notes:
- This change does NOT trigger update-initramfs; only applies to the running system's console. Delphix
doesn't have TTY interactions before pivot-root, e.g. encrypted root passphrase, and
rescue shell can be done with the default "us" layout.
- dpkg-reconfigure keyboard-configuration is another way to update keymap which would also do update-initramfs which is unnecessary and more involved, mounting and unmounting EFI partition.

Testing Done

Updating to different keyboard layouts and verified dumpkeys(1) produced different key mappings.

-rw-r-----  1 delphix staff 470395 Oct 24 19:19 dumpkeys.gb
-rw-r-----  1 delphix staff 446504 Oct 24 19:21 dumpkeys.jp
-rw-r-----  1 delphix staff 453750 Oct 24 19:21 dumpkeys.us.1
-rw-r-----  1 delphix staff 477181 Oct 24 19:23 dumpkeys.de