Rollup merge of #131746 - slanterns:once_box_order, r=joboet

Relax a memory order in `once_box`

per https://github.com/rust-lang/rust/pull/131094#discussion_r1788536445.

In the successful path we don't need `Acquire` since we don't care if the store in `f()` happened in other threads has become visible to the current thread. We'll use our own results instead and just using `Release` to ensure other threads can see our store to `Box` when they fail the `compare_exchange` will suffice.

Also took https://marabos.nl/atomics/memory-ordering.html#example-lazy-initialization-with-indirection as a reference.

`@rustbot` label: +T-libs

r? `@ibraheemdev`

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