refactor: Reverted selected state for explore tab icon cp-7.69.1 cp-7.70.0 (#27459)

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## **Description**

Updates the Explore (Trending) tab icon in the main tab bar from the
filled variant to the outline variant.

## **Changelog**

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CHANGELOG entry: Updated Explore tab icon in the main tab bar to use the
outline style.

## **Related issues**

Fixes: https://consensyssoftware.atlassian.net/browse/DSYS-578

## **Manual testing steps**

```gherkin
Feature: Explore tab icon in tab bar

  Scenario: Explore tab shows outline search icon
    Given the app is open and the user is on any main tab

    When the user views the tab bar
    Then the Explore (Trending) tab shows the outline search icon (not the filled variant)
    And the icon is visible and correctly aligned with other tab icons
```

## **Screenshots/Recordings**

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before and after of your change. -->

### **Before**

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### **After**


https://github.com/user-attachments/assets/e9d96e13-1420-4db6-8353-3de9fd0b06a9


<!-- [screenshots/recordings] -->

## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask Mobile
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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
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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]
> **Low Risk**
> Low risk visual-only change that swaps the selected-state icon for the
Explore/Trending tab; no navigation, analytics, or data flows are
affected.
> 
> **Overview**
> Updates the TabBar selected-state icon mapping for the
Explore/Trending tab to use the outline `IconName.Search` instead of the
filled `IconName.SearchFilled`, reverting its “active” appearance to
match the outline style.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
829d018. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: brianacnguyen

app/component-library/components/Navigation/TabBar/TabBar.tsx

@@ -33,7 +33,7 @@ import { useAccountMenuEnabled } from '../../../../selectors/featureFlagControll
 const FILLED_ICONS: Partial<Record<TabBarIconKey, IconName>> = {
   [TabBarIconKey.Wallet]: IconName.HomeFilled,
   [TabBarIconKey.Activity]: IconName.ClockFilled,
-  [TabBarIconKey.Trending]: IconName.SearchFilled,
+  [TabBarIconKey.Trending]: IconName.Search,
   [TabBarIconKey.Rewards]: IconName.MetamaskFoxFilled,
 };