Re-enable AppArmor kernel ABI pinning

If we don't do that when we update AppArmor to 3.0.8-2 or newer, we'll re-introduce Tails 5.0~beta1 takes 20% longer to boot than 4.28 (#18906 - closed).

We'll need to re-add kernel-features=/usr/share/apparmor-features/features, which we disabled in 6884f809