fix: overlay preparation on tokio

[klkvr]

this might block and thus should not be spawned on rayon

[github-actions]

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reth-chain-state: patch
reth-engine-tree: patch
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Added a debug assertion in `wait_cloned` to prevent it from being called on a rayon worker thread. Fixed overlay preparation in the engine tree to use `tokio::task::spawn_blocking` instead of `rayon::spawn` to avoid blocking rayon threads.

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