midx-write: revert use of --stdin-packs
This reverts b7d6f23a171 (midx-write.c: use `--stdin-packs` when repacking, 2024-04-01) and then marks the test created in the previous change as passing. The fundamental issue with the reverted change is that the focus on pack-files separates the object selection from how the multi-pack-index selects a single pack-file for an object ID with multiple copies among the tracked pack-files. The change was made with the intention of improving delta compression in the resulting pack-file, but that can be resolved with the existing object list mechanism. There are other potential pitfalls of doing an object walk at this time if the repository is a blobless partial clone, and that will require additional testing on top of the one that changes here. Signed-off-by: Derrick Stolee <stolee@gmail.com> Acked-by: Taylor Blau <me@ttaylorr.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>