we need to implement this on aurora in 2026

zirconium-dev/zirconium@05f3e9c

Basically 2 changes at once, add a workaround we will probably have to keep for a very long time to undo nastiness of the hhd/rechunker (documented in the files of the mentioned commit) and utilize the rpm-ostree rechunker to reduce our update deltas again.

Related upstream issues/PRs:

• [BUG] build-chunked-oci does not place initramfs in its own layer coreos/rpm-ostree#5544
• container-encapsulate: Mark initramfs as exclusive component coreos/rpm-ostree#5535
• build-chunked-oci crashes if target image used as baseline and xattrs for non-rpm contents has changed coreos/rpm-ostree#5545
• ostree-ext: Make new packing if using prior build fails bootc-dev/bootc#1880
• ostree-ext: Failed assertion in Chunking::process_mapping bootc-dev/bootc#1885
• https://gitlab.com/fedora/bootc/tracker/-/issues/82

This would make things considerably nicer

• build-chunked-oci: Add --previous-build option coreos/rpm-ostree#5548

Need to steal this as well:

• feat: "rebalance" chunked layer plan once per month secureblue/secureblue#1824
• chore: clear dnf transaction history from build secureblue/secureblue#1856
• chore: eliminate dependence of initramfs on build date secureblue/secureblue#1923