Scoru: fix flakiness in refutation games.

Context

Replaces !6088 (closed)

The scenario behind the flakiness is:

1. Keen strategy slightly change the inputs
2. Both players evaluate their inputs, but eventually diverge on a tick.
3. However, they reach the same final state hash for the commitment.
4. Thus, no conflict, no game, no outcome.

Instead of assuming that both players have different state hashes, we only check if they agree on the final state hash.

Manually testing the MR

while dune exec ./test_refutation_game.exe ; do done

Checklist

• n/a Document the interface of any function added or modified (see the coding guidelines)
• n/a Document any change to the user interface, including configuration parameters (see node configuration)
• n/a Provide automatic testing (see the testing guide).
• n/a For new features and bug fixes, add an item in the appropriate changelog (docs/protocols/alpha.rst for the protocol and the environment, CHANGES.rst at the root of the repository for everything else).
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• Select as Assignee the next person who should take action on that MR