Update the hardfork in the transaction common used to estimate L1 opt… (#22997)

…imism fees to London, fixing display of Layer 1 optimsim fees

## **Description**

The bug was that Layer 1 fees were not being displayed on the
confirmation screen for transactions on Optimism.

This was because `estimatedL1Fees` was null, because
`fetchEstimatedL1Fee` was failing, because
`TransactionFactory.fromTxData(txParams, { common })` in
`buildUnserializedTransaction` was throwing an error, because `txParams`
has a `type` === `2`, but EIP-1559 transactions are not supported on the
spurious dragon hardfork, which is what was being used in the `common`
configuration of that `TransactionFactory.fromTxData` call.

This became a problem after
https://github.com/MetaMask/core/pull/3817/files. That PR correctly
fixed a bug which could result in the transaction type being removed
from the `txMeta.txParams` when `addTransaction` in the tx controller
was called. With that bug fix, there was now a `type` present on the
`txParams` that got passed to the aforementioned
`TransactionFactory.fromTxData` call. Prior to that bug fix, there was
no `type` on `txParams` at that point, the ethereumjs-tx
TransactionFactory was treating these transactions as legacy
transactions, and so was constructing a type 0 transaction, and the fact
that the hardfork was spurious dragon was not a problem

This PR fixes the problem by updating the hardfork param used in the
`common` configuration of that `TransactionFactory.fromTxData` call.
This should not have a functional effect, as this will cause no change
in data and value of the tx passed to the smart contract to generate an
fee estimate, except that this may result in more accurate L1 fee
estimates (that is not certain though).

## **Related issues**

Fixes: #22945

## **Manual testing steps**

1. Create a transaction on OP Mainnet
2. Click "Fee details" on the confirmation screen
3.  The layer 1 fee details should be visible

## **Screenshots/Recordings**

### **After**

![Screenshot from 2024-02-16
09-27-25](https://github.com/MetaMask/metamask-extension/assets/7499938/6c759096-f393-4101-b9af-a3542e313571)


## **Pre-merge author checklist**

- [ ] I’ve followed [MetaMask Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/CODING_GUIDELINES.md).
- [ ] I've clearly explained what problem this PR is solving and how it
is solved.
- [ ] I've linked related issues
- [ ] I've included manual testing steps
- [ ] I've included screenshots/recordings if applicable
- [ ] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.
- [ ] I’ve properly set the pull request status:
  - [ ] In case it's not yet "ready for review", I've set it to "draft".
- [ ] In case it's "ready for review", I've changed it from "draft" to
"non-draft".

## **Pre-merge reviewer checklist**

- [ ] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [ ] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

Author: danjm

ui/helpers/utils/optimism/buildUnserializedTransaction.js

@@ -22,7 +22,7 @@ function buildTransactionCommon(txMeta) {
     // Optimism only supports type-0 transactions; it does not support any of
     // the newer EIPs since EIP-155. Source:
     // <https://github.com/ethereum-optimism/optimism/blob/develop/specs/l2geth/transaction-types.md>
-    defaultHardfork: Hardfork.SpuriousDragon,
+    defaultHardfork: Hardfork.London,
   });
 }