MNT Fix test for required password fields in kitchen sink

[GuySartorelli]

Description

Fixes https://github.com/silverstripe/recipe-kitchen-sink/actions/runs/7572648719/job/20622988035

This is caused by the text field template being overridden for the front-end in a CWP module. The way the template is overridden, there's not much we can do to fix the actual functionality in that scenario without adding some hard coupling between PasswordField and ConfirmedPasswordField classes - which isn't really patch release friendly.

This PR changes the test to validate just that it works in the CMS with default templates - it makes no promises about the functionality working on the front-end.

Issues

• Broken builds .github#182

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