chore: disable external TestFlight distribution for RC and production builds (#29998)

---

## **Description**

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also include relevant motivation and context. Have in mind the following
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RC and production iOS builds were not explicitly setting
`distribute_external` when calling `upload-to-testflight.yml`, which
meant they relied on the callee's default. This made the behaviour
implicit and fragile.

This PR explicitly passes `distribute_external: false` in the three
workflows that trigger a TestFlight upload for RC and production builds:

- `auto-rc-ota-build-core.yml` (Auto-RC flow)
- `runway-rc-builds.yml` (Runway manual RC trigger)
- `runway-production-builds.yml` (Runway manual production trigger)

By pinning the flag to `false`, each new RC or production binary is
uploaded to TestFlight for **internal testers only**. External
distribution remains a deliberate, separate step — preventing accidental
early exposure of builds to external groups and allowing multiple RC
builds to be uploaded without immediately surfacing them externally.

## **Changelog**

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`CHANGELOG entry: Added a new tab for users to see their NFTs`
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CHANGELOG entry: null

## **Related issues**

No issue: CI/build workflow maintenance — makes external distribution
behaviour explicit and consistent across all RC and production upload
paths.

## **Manual testing steps**

```gherkin
Feature: TestFlight distribution gating for RC and production builds

  Scenario: RC build is uploaded without external distribution
    Given a release branch exists and a build is triggered via runway-rc-builds.yml
    When the upload-ios-testflight job completes
    Then the IPA is available to internal testers on TestFlight
    And the build is NOT distributed to external testing groups

  Scenario: Production build is uploaded without external distribution
    Given a release branch exists and a build is triggered via runway-production-builds.yml
    When the upload-ios-testflight job completes
    Then the IPA is available to internal testers on TestFlight
    And the build is NOT distributed to external testing groups
```

## **Screenshots/Recordings**

### **Before**

N/A

### **After**

N/A

## **Pre-merge author checklist**

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Unchecked boxes are ambiguous: they are not an implicit "N/A" and they
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- [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.

#### Performance checks (if applicable)

- [x] I've tested on Android
  - Ideally on a mid-range device; emulator is acceptable
- [x] I've tested with a power user scenario
- Use these [power-user
SRPs](https://consensyssoftware.atlassian.net/wiki/spaces/TL1/pages/edit-v2/401401446401?draftShareId=9d77e1e1-4bdc-4be1-9ebb-ccd916988d93)
to import wallets with many accounts and tokens
- [x] I've instrumented key operations with Sentry traces for production
performance metrics
- See [`trace()`](/app/util/trace.ts) for usage and
[`addToken`](/app/components/Views/AddAsset/components/AddCustomToken/AddCustomToken.tsx#L274)
for an example

## **Pre-merge reviewer checklist**

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checklist: an
unchecked box is ambiguous, a checked box means the reviewer consciously
assessed that responsibility. See `docs/readme/ready-for-review.md`.
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- [ ] 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.

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Author: tommasini

.github/workflows/auto-rc-ota-build-core.yml

@@ -142,4 +142,5 @@ jobs:
       build_commit_sha: ${{ needs.trigger-build.outputs.built_commit_sha }}
       build_version: ${{ needs.trigger-build.outputs.semantic_version }}
       build_number: ${{ needs.trigger-build.outputs.ios_version_code }}
+      distribute_external: false
     secrets: inherit

.github/workflows/runway-production-builds.yml

@@ -65,4 +65,5 @@ jobs:
       build_commit_sha: ${{ needs.build.outputs.built_commit_sha }}
       build_version: ${{ needs.build.outputs.semantic_version }}
       build_number: ${{ needs.build.outputs.ios_version_code }}
+      distribute_external: false
     secrets: inherit

.github/workflows/runway-rc-builds.yml

@@ -65,6 +65,7 @@ jobs:
       build_commit_sha: ${{ needs.build.outputs.built_commit_sha }}
       build_version: ${{ needs.build.outputs.semantic_version }}
       build_number: ${{ needs.build.outputs.ios_version_code }}
+      distribute_external: false
     secrets: inherit
 
   slack-notification: