Revert "selinux: When adding userdata labels, do cache too"

This reverts commit 8994907baf46dc1ddd78467ec57ff78639c01937.
Revert "selinux: Use a more reliable sentinel to flag /data labelling"

This reverts commit b52874de531340af02ac8e664d828dcd02d2d860.
Revert "Add SELinux filesystem relabeling to init"

This reverts commit d2d1a7ffb1f5e831ed654379496f0efe88159a66.