…/allowance refresh workaround cp-7.69.0 (#27162)

## **Description**

Reverts #26954.

Polymarket has resolved the underlying CLOB infrastructure issue that
was causing intermittent `not enough balance / allowance` 400 errors
during order placement. The temporary `refreshBalanceAllowance()`
workaround (calling `GET /balance-allowance/update` before each order)
is no longer needed and is removed here.

### Changes:
- **`utils.ts`**: Remove `refreshBalanceAllowance()` utility and related
HMAC auth logic
- **`PolymarketProvider.ts`**: Remove the preflight refresh call from
`placeOrder()`
- **`utils.test.ts`**: Remove associated unit tests
- **`PolymarketProvider.test.ts`**: Remove associated integration tests

## **Changelog**

CHANGELOG entry: null

## **Related issues**

Fixes:

## **Manual testing steps**

```gherkin
Feature: Polymarket order placement without refresh workaround

  Scenario: user places a BUY order on a prediction market
    Given the user has USDC deposited in their Polymarket proxy wallet

    When user places a BUY order on any market
    Then the order completes successfully without a preflight refresh call

  Scenario: user places a SELL order on a prediction market
    Given the user holds outcome tokens for a market

    When user places a SELL order
    Then the order completes successfully without a preflight refresh call
```

## **Screenshots/Recordings**

N/A — no UI changes

### **Before**

<!-- N/A -->

### **After**

<!-- N/A -->

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
Coding
Standards](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/CODING_GUIDELINES.md).
- [x] I've completed the PR template to the best of my ability
- [x] I've included tests if applicable
- [x] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] I've applied the right labels on the PR (see [labeling
guidelines](https://github.com/MetaMask/metamask-mobile/blob/main/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **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.

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Changes Polymarket order submission behavior by removing a preflight
balance/allowance refresh; if the upstream CLOB issue is not fully
resolved, this could reintroduce intermittent order failures under load.
> 
> **Overview**
> Removes the temporary Polymarket CLOB *balance/allowance refresh*
workaround by deleting `refreshBalanceAllowance` from `utils.ts` and
dropping the pre-submit call in `PolymarketProvider.placeOrder()`.
> 
> Cleans up the associated unit/integration coverage by removing mocks
and test cases that asserted the refresh call ordering and failure
handling.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
db50f7d. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->