fix(homepage): revert ErrorState icon to design system and center Retry button (#26643)

## **Description**

Fixes two issues in the `ErrorState` component used by Homepage
sections:

1. **Reverts icon to design system**: Replaces the custom PNG image
(`wifi-off.png`) with the design system `Icon` component
(`IconName.WifiOff`), restoring consistency with the design system
approach.

2. **Centers the Retry button**: Adds `self-center` to the Button so it
is horizontally centered within the error state, matching the centered
icon and text above it.

**Changes:**
- Replace `Image` + `wifi-off.png` with `Icon` from
`@metamask/design-system-react-native`
- Remove `ErrorState.styles` import (no longer needed)
- Delete unused `app/images/wifi-off.png` asset
- Add `twClassName="self-center"` to the Retry button

## **Changelog**

CHANGELOG entry: null


## **Related issues**

Refs: https://consensyssoftware.atlassian.net/browse/TMCU-407

## **Manual testing steps**

```gherkin
Feature: ErrorState component fixes

  Scenario: error state shows centered wifi-off icon from design system
    Given a homepage section fails to load

    When the error state is displayed
    Then the wifi-off icon is rendered using the design system Icon component
    And the Retry button is horizontally centered below the error message
```

## **Screenshots/Recordings**

### **Before**

<img width="300"
src="https://github.com/user-attachments/assets/b71ad654-ff73-440c-a84e-09a4d34ac730"
/>
<img width="300"
src="https://github.com/user-attachments/assets/82f28853-08db-4543-983a-e3a842af2c59"
/>


### **After**

<img width="300"
src="https://github.com/user-attachments/assets/bcc8480c-c1d5-4efc-bfa2-81aba1dc6ce2"
/>
<img width="300"
src="https://github.com/user-attachments/assets/4353c7dd-9194-4b09-9e37-0f30d6b12d2b"
/>
<!-- Design system icon, button centered -->

## **Pre-merge author checklist**

- [x] I have 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 have completed the PR template to the best of my ability
- [x] I have included tests if applicable
- [x] I have documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I have 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 have 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]
> **Low Risk**
> Low risk UI-only change that swaps a local PNG/styled `Image` for a
design-system `Icon` and tweaks button alignment; no business logic or
data handling changes.
> 
> **Overview**
> Updates the Homepage `ErrorState` UI to use the design system `Icon`
(`IconName.WifiOff`, muted XL) instead of a bundled `wifi-off.png` +
`StyleSheet` styles, and removes the now-unused `ErrorState.styles.ts`.
> 
> Centers the Retry button by adding `twClassName="self-center"`.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
8fe53f4. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: wachunei

app/components/Views/Homepage/components/ErrorState/ErrorState.styles.ts

@@ -1,8 +1,11 @@
 import React from 'react';
-import { Image } from 'react-native';
 import {
   Box,
   Text,
+  Icon,
+  IconName,
+  IconSize,
+  IconColor,
   TextVariant,
   TextColor,
   BoxAlignItems,
@@ -11,8 +14,6 @@ import {
   ButtonSize,
 } from '@metamask/design-system-react-native';
 import { strings } from '../../../../../../locales/i18n';
-import wifiOffIcon from '../../../../../images/wifi-off.png';
-import styles from './ErrorState.styles';
 
 interface ErrorStateProps {
   /** Text describing what failed to load (e.g., "Unable to load predictions") */
@@ -41,7 +42,11 @@ const ErrorState: React.FC<ErrorStateProps> = ({ title, onRetry }) => {
 
   return (
     <Box alignItems={BoxAlignItems.Center} gap={3} padding={4}>
-      <Image source={wifiOffIcon} style={styles.icon} />
+      <Icon
+        name={IconName.WifiOff}
+        size={IconSize.Xl}
+        color={IconColor.IconMuted}
+      />
       <Text
         variant={TextVariant.BodyMd}
         color={TextColor.TextAlternative}
@@ -53,6 +58,7 @@ const ErrorState: React.FC<ErrorStateProps> = ({ title, onRetry }) => {
         variant={ButtonVariant.Secondary}
         size={ButtonSize.Lg}
         onPress={handleRetry}
+        twClassName={'self-center'}
       >
         {strings('homepage.error.retry')}
       </Button>