releng: /etc/pacman.d/hooks/ will be used when running pacstrap in the live environment

Due to FS#49347, all hooks in /etc/pacman.d/hooks will be used by pacstrap. This means that hooks in /configs/releng/airootfs/etc/pacman.d/hooks/ will run when users execute pacstrap in the live environment to install their system.

This is already the case when following Install Arch Linux from existing Linux, but for archiso it could be prevented by having the hooks delete themselves after running. Thus they would not be in the airootfs image.