…g mode in branch.json cp-7.71.0 (#27879)

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## **Description**

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also include relevant motivation and context. Have in mind the following
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1. What is the reason for the change?
2. What is the improvement/solution?
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`branch.json` had `useTestInstance: true` and `debugMode: true`, which
forced **all builds** — including production RC — to initialize the
Branch SDK against the **test environment**. Branch short links (e.g.
`metamask.app.link/1WkF6GmE40b`) are created in the **live** Branch
dashboard, so the test-instance SDK could never resolve them: the test
and live environments are separate databases.

This was the root cause of the "This page doesn't exist" error when
opening Branch deepview short links (e.g. from Twitter/X). The SDK
returned `+clicked_branch_link: false` and `+non_branch_link` with the
raw URL because the test environment had no record of live links.

The fix sets both values to `false` so the SDK uses the live key from
the native configuration (`Info.plist` / `AndroidManifest.xml`),
matching the environment where links are actually created.

**Note:** The same `branch.json` content is also present at
`android/app/src/main/assets/branch.json` — both platforms are affected.
This PR fixes the root config; the Android copy should also be
verified/updated.

## **Changelog**

CHANGELOG entry: Fixed Branch.io deep links not resolving by switching
SDK from test to live environment

## **Related issues**

Fixes:

## **Manual testing steps**

```gherkin
Feature: Branch short link deep linking

  Background:
    Given I have a production RC build installed
    And the app is using the live Branch key

  Scenario: user opens a Branch short link from cold start
    Given the app is not running

    When user taps a Branch deepview link (e.g. https://metamask.app.link/1WkF6GmE40b)
    Then the app should open
    And the user should be navigated to the intended destination (e.g. Trending page)
    And the "This page doesn't exist" modal should NOT appear

  Scenario: user opens a Branch short link from warm start (app backgrounded)
    Given the app is running in the background

    When user taps a Branch deepview link
    Then the app should come to foreground
    And the user should be navigated to the intended destination

  Scenario: user opens a direct universal link (non-Branch)
    Given the app is installed

    When user taps https://link.metamask.io/trending
    Then the Trending page should open normally
    And behavior should be unchanged from before this PR
```

## **Screenshots/Recordings**

### **Before**

N/A

### **After**

N/A

## **Pre-merge author checklist**

- [x] 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).
- [x] I've completed the PR template to the best of my ability
- [x] I've included tests if applicable
- [x] I've documented my code using [JSDoc](https://jsdoc.app/) format
if applicable
- [x] 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**

- [x] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [x] 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 config-only change, but it affects deep link behavior across
builds by switching Branch initialization away from the test
environment.
> 
> **Overview**
> Disables `debugMode` and `useTestInstance` in `branch.json`, ensuring
the Branch SDK initializes against the **live** environment rather than
the test instance.
> 
> This should restore proper resolution of production Branch short
links/deepviews that previously failed when the app was forced to use
the test Branch database.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
33fcef1. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->