zk_reveal: Wasm PVM can produce partial reveal partial raw data

Context

Fixes #5527.

Manually testing the MR

dune exec src/lib_scoru_wasm/test/main.exe -- --file test_reveal.ml --title "test lib scoru wasm: Reveal (Test reveal_partial_preimage with preimage length below max_bytes (2.0.0))" --verbose

Checklist

• Document the interface of any function added or modified (see the coding guidelines)
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• Provide automatic testing (see the testing guide).
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