Remove 'ui' tests form forms element

... because they rely on UA having different rendering in the non-shadow DOM.

In other words, that means that a <input type='foo'> that has the same size, color, backrgound color, text alignment than <input type='text'> will be considered as not implemented even if there are anonymous content showing a different UI and/or a UI poping up when the element is clicked.

This test is dangerous because it might make UA to implement input types differently just to pass it.

As a side note, I haven't removed the "blacklists" because I believe it could be a way to give negative points when a UA is just pretending to support something. This said, this requires subjective opinion which can be unfair...