* test: Default to enabling fault proofs

* test: replace useFaultProofs with useLegacyContracts

Note that this does not modify the deploy config, which still uses the
same `useFaultProofs` flag. It simply modifies the state variables in
CommonTest

* chore: Update gas snapshot

* fix: enableLegacy on L2OO invariants

* feat: Add comment

* fix: enableLegacy on portal invariants

* fix: enableLegacy on Initializable.t.sol

* fix: enableLegacy on portal tests

* feat: follow convention of super.enable...()

* fix: Don't double enable