This will help us detect if any of this happens:

 - config/chroot_local-hooks/99-initramfs-compress is broken

 - live-build does not generate the initramfs after
   config/chroot_local-hooks/99-initramfs-compress has applied
   our preferred configuration

 - Some unrelated change makes the initramfs substantially larger,
   as an unintended side-effect.

As of Tails 3.12.1, our current initramfs is 30M large so a 35M
limit should give us just enough safety margin.