fix(fault_proof): fix defend logic

[fakedev9999]

Summary

This PR modifies the get_oldest_game_address function to accept a parameter that determines whether to check for equality or inequality between the output root and the claim.

Problem

The get_oldest_game_address function is used for both defense (get_oldest_defensible_game_address) and challenging (get_oldest_challengable_game_address).

For challenging, we should challenge games where the claimed root doesn't match the actual output root (the current logic is correct for this)

For defending, we should defend games where the claimed root does match the actual output root (the current logic is incorrect for this)

So for defense, we want the opposite condition: if output_root == game_claim. This would mean we're defending games where the claim is correct but a challenge occurred.

[ratankaliani]

LGTM!