gh-130313: Avoid locking when clearing objects

[DinoV]

There's no need for us to lock the object when clearing the managed dict. We may need to lock the dict if it's been materialized and points to external objects as we could be doing a simple free of the object while other things refer to the dict.

This requires us to relax an assert because we clear objects after we've restarted the world. But we're past the point of resurrection so no one else can be referring to this object.

https://github.com/facebookexperimental/free-threading-benchmarking/tree/main/results/bm-20250214-3.14.0a5+-c00cd86-NOGIL

• Issue: We shouldn't lock to clear an object #130313

[colesbury]

See comment about clear_inline_values, but otherwise LGTM.

It might be worth running the refleak build bots because these code paths are tricky.

[colesbury]

Does this need to be FT_ATOMIC_STORE_UINT8(values->valid, 0) for the call from set_dict_inline_values?