fix: Updated main navigator to conditionally show rewards or settings tab (MetaMask#22199)

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## **Description**
This PR updated main navigator to conditionally show rewards or settings
tab
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## **Related issues**

Fixes:

## **Manual testing steps**

```gherkin
Feature: my feature name

  Scenario: user [verb for user action]
    Given [describe expected initial app state]

    When user [verb for user action]
    Then [describe expected outcome]
```

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/>

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### **After**
<img width="1290" height="2796" alt="Simulator Screenshot - iPhone 15
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src="https://github.com/user-attachments/assets/e131190b-cdbb-4d73-b90a-ac6049141f11"
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<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> Home tab bar now displays Rewards when enabled; otherwise Settings,
removing the always-present Settings tab.
> 
> - **Navigation**:
>   - **HomeTabs (`app/components/Nav/Main/MainNavigator.js`)**:
> - Conditionally render either `Routes.REWARDS_VIEW` or
`Routes.SETTINGS_VIEW` based on `isRewardsEnabled`.
> - Remove the unconditional `Routes.SETTINGS_VIEW` tab to prevent both
tabs appearing simultaneously.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
86e7f21. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: brianacnguyen

app/components/Nav/Main/MainNavigator.js

@@ -695,20 +695,21 @@ const HomeTabs = () => {
         component={TransactionsHome}
         layout={({ children }) => <UnmountOnBlur>{children}</UnmountOnBlur>}
       />
-      {isRewardsEnabled && (
+      {isRewardsEnabled ? (
         <Tab.Screen
           name={Routes.REWARDS_VIEW}
           options={options.rewards}
           component={RewardsHome}
           layout={({ children }) => UnmountOnBlurComponent(children)}
         />
+      ) : (
+        <Tab.Screen
+          name={Routes.SETTINGS_VIEW}
+          options={options.settings}
+          component={SettingsFlow}
+          layout={({ children }) => UnmountOnBlurComponent(children)}
+        />
       )}
-      <Tab.Screen
-        name={Routes.SETTINGS_VIEW}
-        options={options.settings}
-        component={SettingsFlow}
-        layout={({ children }) => UnmountOnBlurComponent(children)}
-      />
     </Tab.Navigator>
   );
 };