[Discover] Styling of "Document" when image field formatter is used

[timroes]

When having a field configured using the image field formatter (URL > img), the way the summarized "Document" view is shown feels a bit off:

Because currently the text is aligning to the bottom of the image it actually can "push" the text out of the clipped height leaving that above weird view.

It's more obvious what happens when using a higher truncation size:

I don't think this is the ideal presentation when using images, so we should check if we can optimize that. I am not sure if simply aligning to the top is better, since it might cause weird effects with different height texts, so we might need to play around a bit.

This view leads to a couple of more problems when used in data grid, since datagrid doesn't hide overflows (see elastic/eui#4959), leading to a slightly weirder UX, e.g. when selecting cells:

[elasticmachine]

Pinging @elastic/kibana-app (Team:KibanaApp)