bless autodiff batching test
This pr blesses a broken test and unblocks running rust in the Enzyme CI: https://github.com/EnzymeAD/Enzyme/pull/2430
Enzyme is the plugin used by our std::autodiff and (future) std::batching modules, both of which are not build by default.
In the near future we also hope to enable std::autodiff in the Rust CI.
This test is the only one to combine two features, automatic differentiation and batching/vectorization. This combination is even more experimental than either feature on its own. I have a wip branch in which I enable more vectorization/batching and as part of that I'll think more about how to write those tests in a robust way (and likely change the interface). Until that lands, I don't care too much about what specific IR we generate here; it's just nice to track changes.
r? compiler
a84359c5a7