Comment 6 for bug 1884758

Compat thoughts
- as is we need to keep ipxe-qemu-256k-compat-efi-roms as long as we support guests started and not restarted ever since Bionic which translates to Bionic support time ~2028
- if we can revert the size from 512k to 256k nnow we still need it installed and
  around the same time.
  - We just would need another qemu delta on machine types to know about the size change
  - And we'd break backwards migration again.

There is actually no gain in using the new size, but in turn I'd need to be able to pad the rom's to be inside 256-512k without breaking them functionally.