Fix criteria form

[lovincyrus]

Fix https://www.notion.so/rilldata/v0-50-0-QA-114ba33c8f5780bd897ecb99547ed623#114ba33c8f5780c29dbedd81e2cf7f8e

[briangregoryholmes]

The Notion doc is referring to a different element of the form. I'm also not able to reproduce the Notion screenshot to begin with. The default behavior of the Select component is to fully fit the label, so I'm not totally sure where this issue would have come from.

As for the last element, it's not really that you want width to be "null", but rather "auto" or some fixed value like "120px". I'd rather not accept null here.

That said, I do see some issues with the Select component not always respecting the width property (it fits rather than sets a fixed width). I can look into that.

A larger issue is that this form does not appear to function properly. The measure name dropdown for each criteria only ever has one option and the ids are in conflict, so the triggers open up menus in the wrong places (though they do work). That latter one may have only surfaced when moving to shadcn a few weeks ago.