[DataGrid] Cell expansion missing border in Safari

[kertal]

With some of the latest changes EuiDataGrid's cell expansion is missing a border /shadow when using Safari

Safari 15.5

*Chrome 104

Noticed while testing Safari

[chandlerprall]

Confirmed for me in Safari 15.4; looks like the shadow is present in those rounded corners but clipped to the element's bounding box.

[cee-chen]

It's the overflow: auto on .euiDataGridRowCell__popover combined with the new filter: drop-shadow (vs box-shadow) added in #5977:

Unfortunately, we need that overflow: auto for cells with very large content:

Based on the Emotion PR, the switch to filter was added to accommodate the popover arrow which EuiDataGrid simply doesn't need (we hide the arrow). I'm leaning towards removing the filter for EuiDataGrid and re-adding the box-shadow CSS.