contracts: Fix OZ-M-02 by removing donateEth()

packages/contracts-bedrock/contracts/test/L1StandardBridge.t.sol

@@ -390,13 +390,4 @@ contract L1StandardBridge_Test is Bridge_Initializer {
             hex""
         );
     }
-
-    // donateETH
-    // - can send ETH to the contract
-    function test_donateETH() external {
-        assertEq(address(L1Bridge).balance, 0);
-        vm.prank(alice);
-        L1Bridge.donateETH{ value: 1000 }();
-        assertEq(address(L1Bridge).balance, 1000);
-    }
 }

packages/contracts-bedrock/contracts/universal/StandardBridge.sol

@@ -128,11 +128,6 @@ abstract contract StandardBridge {
      * Public Functions *
      ********************/
 
-    /**
-     * @notice Send ETH to this contract. This is used during upgrades
-     */
-    function donateETH() external payable {}
-
     /**
      * @notice EOAs can simply send ETH to this contract to have it be deposited
      * to L2 through the standard bridge.