Make it possible to force rebuild of debootstrap-image
The filename of container images created by projects/debootstrap-image does not include var/build_id or any version number, so it doesn't get rebuilt automatically when the build instructions change.
However in some cases such as #29158 (moved) we want to force those images to be rebuilt.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information