chore: Remove unused test helpers

.changeset/few-boxes-pull.md

+---
+'@eth-optimism/contracts': patch
+---
+
+Remove unused gas testing utils

packages/contracts/contracts/test-helpers/Helper_GasMeasurer.sol

-// SPDX-License-Identifier: MIT
-pragma solidity ^0.8.9;
-
-contract Helper_GasMeasurer {
-    function measureCallGas(address _target, bytes memory _data) public returns (uint256) {
-        uint256 gasBefore;
-        uint256 gasAfter;
-
-        uint256 calldataStart;
-        uint256 calldataLength;
-        assembly {
-            calldataStart := add(_data, 0x20)
-            calldataLength := mload(_data)
-        }
-
-        bool success;
-        assembly {
-            gasBefore := gas()
-            success := call(gas(), _target, 0, calldataStart, calldataLength, 0, 0)
-            gasAfter := gas()
-        }
-        require(success, "Call failed, but calls we want to measure gas for should succeed!");
-
-        return gasBefore - gasAfter;
-    }
-}

packages/contracts/test/helpers/gas/gas.ts

-import { ethers } from 'hardhat'
-import { Contract, Signer } from 'ethers'
-
-export class GasMeasurement {
-  GasMeasurementContract: Contract
-
-  public async init(wallet: Signer) {
-    this.GasMeasurementContract = await (
-      await (await ethers.getContractFactory('Helper_GasMeasurer')).deploy()
-    ).connect(wallet)
-  }
-
-  public async getGasCost(
-    targetContract: Contract,
-    methodName: string,
-    methodArgs: Array<any> = []
-  ): Promise<number> {
-    const gasCost: number =
-      await this.GasMeasurementContract.callStatic.measureCallGas(
-        targetContract.address,
-        targetContract.interface.encodeFunctionData(methodName, methodArgs)
-      )
-
-    return gasCost
-  }
-}

packages/contracts/test/helpers/gas/index.ts

-export * from './gas'

packages/contracts/test/helpers/index.ts

@@ -5,4 +5,3 @@ export * from './utils'
 export * from './codec'
 export * from './test-runner'
 export * from './trie'
-export * from './gas'