Remove $LFS/{bin,lib,sbin} from the chown commands

[Xi Ruoyao]

They are symlinks and running chown on a symlink actually operates on the target of the link, and the targets of these links are already covered by $LFS/usr/*. So running chown on them are redundant, and it's potentially harmful if the user wrongly types

for i in bin lib sbin; do
  ln -sv /usr/$i $LFS/$i
done

(note that the additional "/" before usr) in Creating a Limited Directory Layout in the LFS Filesystem: in this case /usr/lib of the host will be owned by the LFS user, and when we install Glibc in chapter 5 it'll just overwrite the Glibc of the host distro, blowing it up.

While we may argue "user error is user error" it's still better to prevent a single-point failure from blowing up the entire host distro. And I cannot see any bad effect to remove them.

Maybe we can even do it before 12.3 release but I'm not sure, so leaving the milestone 12.4 for now.