Bug 1816066 - Fix verifyMultipleLoginsSelectionsTest UI test

[AndiAJ]

Summary:

• The UI test was flaky due to the fact that after filling out the second time the loging credentials the click on the submit button wasn't performed properly in some cases
• Instead of clicking the "Submit" button it looks like the password text box got clicked again selecting the previously added string, launching the text selection toolbar

• I think that the click was poorly performed because of sync problems, namely the credential filing actions were performed way to fast causing inconsistencies
• To overcome this problem, I've created the waitForAppWindowToBeUpdated function which will wait for waitingTimeVeryShort(1 sec) for the app window do be updated after each login credential filing action.

The UI test successfully passed 200x 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=1816066