Don't install /boot/intel-ucode.img anymore

Considering that mkinitcpio has been prepending microcode from /usr/lib/firmware/intel-ucode by default for months now, (archlinux/mkinitcpio/mkinitcpio!291 (merged)), shouldn't building and installing intel-ucode.img be skipped ?

This would have to be followed with

• Proper announcement in case some old setups still rely on intel-ucode.img (i.e. not using 'microcode' mkinitcpio HOOK)
• Update https://wiki.archlinux.org/title/Microcode
• Update https://wiki.archlinux.org/title/Mkinitcpio
• Update https://wiki.archlinux.org/title/Unified_kernel_image
• Update https://wiki.archlinux.org/title/Systemd-boot and other boot loaders
• Remove 'backup' path from mkinitcpio: https://gitlab.archlinux.org/archlinux/mkinitcpio/mkinitcpio/-/blob/master/install/microcode#L87
• Dracut and mkosi-initrd support directly using the firmware files. Not sure booster does, but does supporting booster warrant building & installing intel-ucode.img in every other users' /boot ?