static-delta: Drop flat per-part decompression-size cap

static-delta: Drop flat per-part decompression-size cap

The 512 MiB flat cap on decompressed part size is heuristic.
Since we broke flatpak firefox deltas with incorrect heuristics,
back that out until we come up with a design that is precise and
tighter.

This deliberately reopens <https://github.com/ostreedev/ostree/security/advisories/GHSA-7cgc-gp99-6jmm> for now.

Assisted-by: https://github.com/cgwalters/cgwalters#llms
Signed-off-by: Colin Walters <walters@verbum.org>