Revert "arch-chroot: bind mount over a /etc/resolv.conf symlink"

This reverts commit 4d3aec66.

util-linux upstream has reverted https://github.com/util-linux/util-linux/commit/1b2d8187360157b00b47f52522fc039d82e34e6b due to regression, and we cannot rely on --no-canonicalize to mount over symlink. Furthermore, the canonicalization of the source resolv.conf should not be disabled, otherwise a symlink to a file on host might be bind mounted into chroot, which would still behave spuriously.

Hence, let's revert this for now. A new mount option X-mount.nocanonicalize= is scheduled for util-linux v2.41 which adds fine-grained control in that regard. A FIXME is added to make use of that later.

cc @nl6720