Bug 1877440 - Use only TestHelper snack bar verification function in UI tests

[AndiAJ]

Summary:

• As mentioned in #5313 the verifySnackBarText function from the CollectionRobot didn't assert anything, only waited for an item containing text
• Based on this, I've decided to use only the function from TestHelper in all UI tests as we were using this snackbar text verification in multiple robots, mostly having the same implementation, doing the same thing
• The snackbar text verification done in the normal and compose createCollectionByLongPressingOpenTabsTest UI tests were actually incorrect and because we weren't properly doing an assertion it passed even if we were checking an incorrect string(as mentioned above, the verifySnackBarText function from the CollectionRobot didn't assert anything, only waited for an item containing text)
• Successfully ran all UI test 3x on Firebase ✅

Pull Request checklist

• Quality: This PR builds and passes detekt/ktlint checks (A pre-push hook is recommended)
• Tests: This PR includes thorough tests or an explanation of why it does not
• Changelog: This PR includes a changelog entry or does not need one
• Accessibility: The code in this PR follows accessibility best practices or does not include any user facing features

After merge

• Breaking Changes: If this is a breaking Android Components change, please push a draft PR on Reference Browser to address the breaking issues.

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GitHub Automation

https://bugzilla.mozilla.org/show_bug.cgi?id=1877440

[jjSDET]

really good catch here.