* op-e2e: Remove TestCannonChallengeWithCorrectRoot

Challenging with the correct root is already covered by TestOutputCannonPoisonedPostState

* op-e2e: Switch multi game test to use output bisection

Remove the multiple cannon games test - we have unit tests checking the games are separate enough that we don't need this additional coverage.

* op-e2e: Remove cannon helpers

* op-e2e: Update multi game test to use claim helpers.