Fix flaky UI tests caused by AmbiguousViewMatcherException and other refactoring work

[AndiAJ]

• Fix flaky tests caused by AmbiguousViewMatcherException
Both me and @sv-ohorvath ran the affected tests 150x on Firebase and successfully passed.

• Removed closeTabViaXButton() and replace it with closeTab() in the UI tests (have the same applicability)
• Removed openNewTabAndEnterToBrowser() and replace it with enterURLAndEnterToBrowser() in the UI tests (have the same applicability)

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.

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[isabelrios]

Changes look good to me, thanks for the investigation and fix