This reverts the change from #7012.
Referrer manifests may be pushed before their subject, and the OCI distribution spec requires registries to initially accept a manifest whose subject does not exist yet. Keep BuildKit's default push order aligned with that behavior instead of working around registries that reject this flow.
Signed-off-by: CrazyMax <1951866+crazy-max@users.noreply.github.com>
(cherry picked from commit 409c8da50f)
b4e609fb7c