fault-detector: fixup test import

packages/fault-detector/test/helpers.spec.ts

 import hre from 'hardhat'
+import '@nomiclabs/hardhat-ethers'
 import { Contract, utils } from 'ethers'
 import { toRpcHexString } from '@eth-optimism/core-utils'
-import { getContractFactory } from '@eth-optimism/contracts-bedrock'
+import Artifact__L2OutputOracle from '@eth-optimism/contracts-bedrock/forge-artifacts/L2OutputOracle.sol/L2OutputOracle.json'
 import { SignerWithAddress } from '@nomiclabs/hardhat-ethers/signers'
 
 import { expect } from './setup'
@@ -26,7 +27,13 @@ describe('helpers', () => {
 
   let L2OutputOracle: Contract
   beforeEach(async () => {
-    L2OutputOracle = await getContractFactory('L2OutputOracle', signer).deploy(
+    const Factory__L2OutputOracle = new hre.ethers.ContractFactory(
+      Artifact__L2OutputOracle.abi,
+      Artifact__L2OutputOracle.bytecode.object,
+      signer
+    )
+
+    L2OutputOracle = await Factory__L2OutputOracle.deploy(
       deployConfig.l2OutputOracleSubmissionInterval,
       deployConfig.l2BlockTime,
       deployConfig.l2OutputOracleStartingBlockNumber,