For #7887 fix flaky verifyDownloadedFileOnStorageTest UI test

[AndiAJ]

For #7887 fix flaky verifyDownloadedFileOnStorageTest UI test ✅ successfully passed 100x. on Firebase

Summary: For verifying that the downloaded file is actually saved on the device, we used similar code with what we have in AC to handle downloads.

Rarely, the test was flaky, failing to verify that the file is actually saved on the device storage (not sure why the returned download uri was null)

As an alternative, @Mugurell suggested to try using the implementation from this tutorial

I made the changes based on our interest, and it seems to be working properly.

Pull Request checklist

• [ ] Tests: This PR includes thorough tests or an explanation of why it does not
• [ ] Screenshots: This PR includes screenshots or GIFs of the changes made or an explanation of why it does not
• [ ] Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features. In addition, it includes a screenshot of a successful accessibility scan to ensure no new defects are added to the product.

QA

• [ ] QA Needed

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GitHub Automation

Fixes #7887

[AndiAJ]

Adding @Mugurell as a reviewer, to share his thoughts as well. 🤞🏽

[AndiAJ]

Thanks @Mugurell , made the changes as suggested.