[5.3] Fix the selector in login tests when running on https

[brianteeman]

None of the login tests were working as they had only been tested on http When tested in a real work with https the webauthn plugin is also present and the tests all failed

This PR updates the cypress get identifier to more accurately target the login button

Testing Instructions

run the cypress tests with https

 npx cypress run --spec '.\tests\System\integration\api\com_users\Users.cy.js'
 npx cypress run --spec '.\tests\System\integration\site\components\com_users\Login.cy.js'
 npx cypress run --spec '.\tests\System\integration\site\modules\mod_login\Default.cy.js' 

Actual result BEFORE applying this Pull Request

tests fail with error message
CypressError: cy.click()can only be called on a single element. Your subject contained 2 elements. Pass{ multiple: true } if you want to serially click each element.

Expected result AFTER applying this Pull Request

tests complete successfully

Note

This does not resolve the fact that the cypress tests should be running under https otherwise they are incomplete or risky tests

Link to documentations

Please select:

• Documentation link for docs.joomla.org:

• No documentation changes for docs.joomla.org needed

• Pull Request link for manual.joomla.org:

• No documentation changes for manual.joomla.org needed

[laoneo]

Thanks. As soon as we are green here, it will be merged. Despite the fix, you discovered a bigger issue and we should change our tests to https, as in #44835, as this is nowadays the standard.

[brianteeman]

thanks