fix: flaky test `BTC Account - Overview has portfolio button enabled …

…for BTC accounts` (#27017)

<!--
Please submit this PR as a draft initially.
Do not mark it as "Ready for review" until the template has been
completely filled out, and PR status checks have passed at least once.
-->

## **Description**
The way the last 2 assertions are constructed are an anti-pattern, that
give place to a race condition, where we wait for the selector to
appear, but we don't wait for it to be enabled, so it can happen that
when we do the assertion, the button is not yet enabled.

```
const buySellButton = await driver.waitForSelector(
  '[data-testid="coin-overview-buy"]',
);
assert.equal(await buySellButton.isEnabled(), true);

const portfolioButton = await driver.waitForSelector(
  '[data-testid="coin-overview-receive"]',
);
assert.equal(await portfolioButton.isEnabled(), true);
```
![Screenshot from 2024-09-10
11-48-09](https://github.com/user-attachments/assets/70672d6c-5f05-47ea-aaf9-5561131ebf25)


To fix this, we need to directly wait for the element to be enabled
(`findClickableElement`).


[![Open in GitHub
Codespaces](https://github.com/codespaces/badge.svg)](https://codespaces.new/MetaMask/metamask-extension/pull/27017?quickstart=1)

## **Related issues**

Fixes: #27018

## **Manual testing steps**

1. Check ci

## **Screenshots/Recordings**
See how the element Buy is present and it's already enabled but when the
assertion took place, the button was still disabled.


![image](https://github.com/user-attachments/assets/5c97c1a6-2fcf-4697-bdec-6e3dadb9cf24)


## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.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-extension/blob/develop/.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.

test/e2e/flask/btc/btc-account-overview.spec.ts

@@ -1,4 +1,3 @@
-import { strict as assert } from 'assert';
 import { Suite } from 'mocha';
 import { withBtcAccountSnap } from './common-btc';
 
@@ -30,15 +29,13 @@ describe('BTC Account - Overview', function (this: Suite) {
           css: '[disabled]',
         });
 
-        const buySellButton = await driver.waitForSelector(
-          '[data-testid="coin-overview-buy"]',
-        );
-        assert.equal(await buySellButton.isEnabled(), true);
+        // buy sell button
+        await driver.findClickableElement('[data-testid="coin-overview-buy"]');
 
-        const portfolioButton = await driver.waitForSelector(
+        // receive button
+        await driver.findClickableElement(
           '[data-testid="coin-overview-receive"]',
         );
-        assert.equal(await portfolioButton.isEnabled(), true);
       },
     );
   });