test: improve logInWithBalanceValidation function in e2e test (MetaMask#25139)

## **Description**
Remove the delay in function `logInWithBalanceValidation` to avoid
slowing down tests, especially considering its potential extensive
usage.

## **Related issues**

Fixes:

## **Manual testing steps**
E2E tests should all pass.

## **Screenshots/Recordings**

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before and after of your change. -->

### **Before**

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### **After**

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- [x] I've completed the PR template to the best of my ability
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Not required for external contributors.

## **Pre-merge reviewer checklist**

- [x] I've manually tested the PR (e.g. pull and build branch, run the
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Author: chloeYue

test/e2e/helpers.js

@@ -863,7 +863,7 @@ const TEST_SEED_PHRASE_TWO =
 const locateAccountBalanceDOM = async (driver, ganacheServer) => {
   const balance = await ganacheServer.getBalance();
 
-  await driver.findElement({
+  await driver.waitForSelector({
     css: '[data-testid="eth-overview__primary-currency"]',
     text: `${balance} ETH`,
   });
@@ -906,9 +906,8 @@ async function unlockWallet(
 
 const logInWithBalanceValidation = async (driver, ganacheServer) => {
   await unlockWallet(driver);
-  await locateAccountBalanceDOM(driver, ganacheServer);
   // Wait for balance to load
-  await driver.delay(500);
+  await locateAccountBalanceDOM(driver, ganacheServer);
 };
 
 function roundToXDecimalPlaces(number, decimalPlaces) {