Move role/label tests that assert on unrendered elements to tentative

[cookiecrook]

IIRC, HTML does not require some elements (like <optgroup>) to be rendered, and WebDriver doesn’t require a role return value on something unrendered.

So a few tests are failing due to unspecified implementation details. For example:
https://wpt.fyi/results/html-aam/fragile/optgroup-role.html?label=experimental&label=master&aligned

Above should be moved to tentative...

And this new PR (already marked tentative)

• Create optgroup-name-desc.tentative.html wpt#49645

Maybe more.

[cookiecrook]

That test predates my knowledge of the .tentative test name feature, so we can probably get rid of the fragile dir altogether when we go in there…