refactor: removed unused pin-extension module and react-react-respons… (#38509)

…ive-carousel  package

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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?
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In this PR, I removed unused pin-extension module and the
react-responsive-carousel package

Jira Link: https://consensyssoftware.atlassian.net/browse/SL-358

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## **Changelog**

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CHANGELOG entry: removed unused pin-extension module and
react-react-responsive-carousel package

## **Related issues**

Fixes:

## **Manual testing steps**

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## **Screenshots/Recordings**

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## **Pre-merge author checklist**

- [x] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/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-extension/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]
> Removes the unused pin-extension onboarding flow and
`react-responsive-carousel`, updating routes, UI, Lavamoat policies, and
locale strings accordingly.
> 
> - **UI/Onboarding**:
> - Remove pin-extension view: delete
`ui/pages/onboarding-flow/pin-extension/*` and related styles/imports.
> - Drop route `ONBOARDING_PIN_EXTENSION_ROUTE` and associated `<Route>`
from `onboarding-flow.tsx` and `helpers/constants/routes.ts`.
> - **Internationalization**:
> - Remove pin-extension strings across locales in
`app/_locales/*/messages.json`.
> - **Dependencies/Build**:
> - Remove `react-responsive-carousel` from `package.json` and its
transitive `react-easy-swipe`; clean up `yarn.lock`.
> - Remove carousel CSS import from
`ui/pages/onboarding-flow/welcome/index.scss`.
> - **Lavamoat Policies**:
> - Remove `react-responsive-carousel` and `react-easy-swipe` entries
from `lavamoat/*` policy and override files.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
6446ba2. This will update automatically
on new commits. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

---------

Co-authored-by: MetaMask Bot <[email protected]>
Co-authored-by: chaitanyapotti <[email protected]>

Author: 3 people