Comment 20 for bug 1918427

agree with dannf
we should refactor disable_update_initramfs and enable_update_initramfs.
we should not use `which` to determine the executable path.
and always disable update_initramfs or arch-specific package, even those pkgs are not installed.

Is it a good solution that we specific absolute path in disable_update_initramfs?
https://github.com/canonical/curtin/blob/master/curtin/commands/curthooks.py#L117-L124