chore: remove deprecated network selector from settings (#21614)

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## **Description**
The network selector in the settings view is very outdated and
inconsistent with the new Bip-44 UI. This is causing:
- New bugs raised
- Double Developer effort when dealing with networks
- Inconsistencies

Therefore, after consulting with @Tlees-MMI and @alfeng6 we have come to
the conclussion of fully removing it from the settings view. From now on
if users want to do anything related to network management they can use
the network selector from the Wallet Screen. Here is part of the
discussion:

<img width="1092" height="817" alt="image"
src="https://github.com/user-attachments/assets/c0af76be-95de-4e2e-9732-4a1732f284b6"
/>

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## **Changelog**

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CHANGELOG entry: removal of network selector in settings

## **Related issues**

Fixes:
- https://consensyssoftware.atlassian.net/browse/ASSETS-1354 |
#20458
- https://consensyssoftware.atlassian.net/browse/ASSETS-1339 |
#20362

## **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]
```

## **Screenshots/Recordings**

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before and after of your change. -->

### **Before**


https://github.com/user-attachments/assets/f7d86172-3fff-4c64-b185-c4a6698e18f5

### **After**


https://github.com/user-attachments/assets/00b0f9f2-cad2-4aad-8b2d-4f21cf86f0ed

## **Pre-merge author checklist**

- [ ] I’ve 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).
- [ ] I've completed the PR template to the best of my ability
- [ ] I’ve included tests if applicable
- [ ] I’ve documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [ ] I’ve 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'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]
> Removes the deprecated Networks settings screen and entry, shifting
network management to the wallet network switcher and updating
navigation, unit tests, and e2e flows accordingly.
> 
> - **Settings**:
> - Remove `Networks` drawer item and related handler from
`Views/Settings`.
> - **Navigation**:
>   - Remove `NetworksSettings` screen from `MainNavigator`.
> - **NetworksSettings Removal**:
> - Delete `Views/Settings/NetworksSettings` component, unit tests, and
snapshots.
> - **Tests/E2E**:
> - Update `Settings` snapshot and unit tests to exclude
`networks-settings`.
>   - Remove `NETWORKS` selector and page object methods.
> - Refactor e2e flows to manage networks via wallet network switcher
(`WalletView`/`NetworkListModal`) instead of Settings (e.g., add/delete
networks, permission cleanup, localhost helper).
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
d94fbf5. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: juanmigdr

app/components/Nav/Main/MainNavigator.js

@@ -13,7 +13,6 @@ import AdvancedSettings from '../../Views/Settings/AdvancedSettings';
 import BackupAndSyncSettings from '../../Views/Settings/Identity/BackupAndSyncSettings';
 import SecuritySettings from '../../Views/Settings/SecuritySettings';
 import ExperimentalSettings from '../../Views/Settings/ExperimentalSettings';
-import NetworksSettings from '../../Views/Settings/NetworksSettings';
 import NotificationsSettings from '../../Views/Settings/NotificationsSettings';
 import NotificationsView from '../../Views/Notifications';
 import NotificationsDetails from '../../Views/Notifications/Details';
@@ -394,11 +393,6 @@ const SettingsFlow = () => (
       component={ExperimentalSettings}
       options={ExperimentalSettings.navigationOptions}
     />
-    <Stack.Screen
-      name="NetworksSettings"
-      component={NetworksSettings}
-      options={NetworksSettings.navigationOptions}
-    />
     <Stack.Screen
       name="CompanySettings"
       component={AppInformation}