EuiDataGrid can enter an infinite ResizeObserver loop and hang the tab when it has exactly one unsized column inside a size-animating ancestor

[stratoula]

Describe the bug
EuiDataGrid can lock up the browser's main thread indefinitely when two conditions are both true:

1. The grid has exactly one column with no explicit initialWidth.
2. The grid is rendered inside an ancestor whose own size is also being measured/animated via ResizeObserver (e.g. an EuiAccordion that is currently expanding).

You can see it happening at kibana here elastic/kibana#276400

Steps to reproduce

1. Render an EuiDataGrid with exactly one column and no initialWidth set on it.
2. Mount it inside an EuiAccordion (or any container that measures/animates its own size via ResizeObserver) at the moment the accordion opens.
3. Give the accordion enough width that the single stretched column's rendered width lands close to the scrollbar-visibility boundary (in practice this shows up more reliably at certain viewport widths, not all).
4. Observe: a brief visual flicker, then the tab becomes completely unresponsive.

Expected behavior

The grid should settle into a stable layout even with a single unsized column, without relying on a ResizeObserver feedback loop that has no termination condition.

Impact and severity
Very problematic for kibana ES|QL charts but we are mitigating elastic/kibana#276423. Ideally I would like this to be solved at the eui side.

Environment and versions
kibana in main is using 116.5.0