`FormLayout` might not need `autoWidth`

[bedrich-schindler]

From the documentation of FormLayout:

For usage in auto-width Modal, you may need to turn on the autoWidth option for your FormLayout. This prevents FormLayout from unexpectedly growing in browsers that don't support CSS subgrid in cases when there are longer validation messages or help texts.

If you check the documentation of the subgrid, you can see Baseline 2023 tag. This means that at least 2 major versions of Safari and several major versions of other browsers have support of subgrid and this is what we aim for.

I would consider dropping autoWidth as it does not make sense now. We cannot also tests this using Playwright when this is broadly supported.

cc @adamkudrna @mbohal @atmelmicro @lukasbriza