…n for RC and manual builds (#30952)

## **Description**

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RC and manual iOS builds were only uploaded to TestFlight internally
(distributed to Apple internal testers only). This change enables
external distribution to the `MetaMask BETA & Release Candidates`
TestFlight group automatically for all RC build paths.

**Changes:**

- **`runway-rc-builds.yml`** (Runway manual RC trigger): passes
`distribute_external: true` to `upload-to-testflight.yml` so the
resulting IPA is distributed to external testers immediately after
upload.
- **`auto-rc-ota-build-core.yml`** (reusable core for auto RC): adds a
`distribute_external` input (default `false` to keep the interface safe
for other callers) and threads it through to the inner
`upload-ios-testflight` job.
- **`build-rc-auto.yml`** (auto RC on `release/*` push): passes
`distribute_external: true` into `auto-rc-ota-build-core.yml` for the
iOS build job.
- **`build-and-upload-to-testflight.yml`** (manual build + upload
workflow): flips the `distribute_external` default to `true` in both the
`workflow_call` and `workflow_dispatch` input blocks. The
`testflight_group` was already defaulting to `MetaMask BETA & Release
Candidates`.

## **Changelog**

CHANGELOG entry: null

## **Related issues**

Fixes:

## **Manual testing steps**

N/A

## **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.

#### 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

For performance guidelines and tooling, see the [Performance
Guide](https://consensyssoftware.atlassian.net/wiki/spaces/TL1/pages/400085549067/Performance+Guide+for+Engineers).

## **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.

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Made with [Cursor](https://cursor.com)

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Medium Risk**
> Changes release automation defaults so RC and manual iOS builds may
reach external TestFlight groups without an explicit opt-in, which
widens who gets builds but stays within existing upload workflows.
> 
> **Overview**
> RC and manual iOS CI paths now **turn on external TestFlight
distribution by default** instead of stopping at internal-only upload.
> 
> **`auto-rc-ota-build-core.yml`** gains a **`distribute_external`**
workflow input and forwards it to **`upload-to-testflight.yml`**.
**`build-rc-auto.yml`** and **`runway-rc-builds.yml`** set
**`distribute_external: true`** on their iOS upload jobs so automated
and Runway-triggered RC builds reach external testers (e.g. **MetaMask
BETA & Release Candidates**).
> 
> **`build-and-upload-to-testflight.yml`** changes the
**`distribute_external`** default from **`false`** to **`true`** for
both **`workflow_call`** and **`workflow_dispatch`**, so manual
build-and-upload runs distribute externally unless opted out.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
44989c3. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->