…eet on MetaMetrics cp-7.80.0 (#31028)

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## **Description**

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Previously, the push onboarding sheets could trigger analytics.optIn()
when MetaMetrics was off, effectively using the marketing-consent flow
to enable MetaMetrics in a less than clear way. This is not desired.
This PR simplifies the action taken after accepting the push pre-prompt.
It reduces the risk of the existing code.

  This PR:
- Adds a isMetaMetricsEnabled gate in usePushPrePromptVariant so the
marketing_consent variant is never returned when MetaMetrics is off (the
push_permission variant is unaffected)
- Strips analytics.optIn(), updateCachedConsent(), and the
device/user-settings trait generation from useEnableMarketingConsent —
the hook now only operates when MetaMetrics is already on
- Removes is_metrics_opted_in from the ANALYTICS_PREFERENCE_SELECTED
event property, since this flow no longer touches metrics opt-in state
- Adds test coverage for the missing push×MetaMetrics×dataCollection
combinations

## **Changelog**

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CHANGELOG entry: Remove the ability for the push onboarding flow to
toggle MetaMetrics opt-in state.

## **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]
```

## **Screenshots/Recordings**

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### **Before**

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### **After**

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## **Pre-merge author checklist**

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- [ ] 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.

#### Performance checks (if applicable)

- [ ] I've tested on Android
  - Ideally on a mid-range device; emulator is acceptable
- [ ] 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
- [ ] 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**

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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.