fix: add E2E Tests for Multi-RPC Migration and Selection (#26851)

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## **Description**
This PR introduces a series of end-to-end (E2E) tests to validate the
functionality of migrating and selecting multiple RPC configurations in
the application. These tests cover different scenarios to ensure that
the application handles multi-RPC settings correctly, including
migrating to a new RPC setup and selecting RPC endpoints from various
interfaces.

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## **Related issues**

Fixes:

## **Manual testing steps**

1. Run `yarn build:test`
2. Run `yarn test:e2e:single test/e2e/tests/network/multi-rpc.spec.ts
--browser chrome`
3.

## **Screenshots/Recordings**

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before and after of your change. -->

### **Before**

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### **After**

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## **Pre-merge author checklist**

- [ ] I've followed [MetaMask Contributor
Docs](https://github.com/MetaMask/contributor-docs) and [MetaMask
Extension Coding
Standards](https://github.com/MetaMask/metamask-extension/blob/develop/.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-extension/blob/develop/.github/guidelines/LABELING_GUIDELINES.md)).
Not required for external contributors.

## **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.

---------

Co-authored-by: Brian Bergeron <[email protected]>