Description
When using a custom height in SelectPanel (e.g., height: medium), the empty state message is improperly rendered within a scrollbar, even when there is ample space to display the message without a scrollbar. This can be observed in the storybook example for height variations and scroll (https://primer.style/react/storybook/?path=/story/components-selectpanel-examples--height-variations-and-scroll&globals=featureFlags.primer_react_css_modules_ga:!true;featureFlags.primer_react_select_panel_with_modern_action_list:!true). If you type a term such as "dddd" into the search bar, the empty state appears inside a scrollable area, which is not expected.
See attached screenshot for reference:

Expected behavior:
- The empty state message should display without being constrained by an unnecessary scrollbar when there is enough space in the panel.
Steps to reproduce:
- Open the storybook example for SelectPanel height variations and scroll.
- Set the height to medium.
- Type a string like "dddd" in the searchbar to trigger the empty state message.
- Note that the empty state message appears within a scrollable area, even if there's enough space for it to display fully.
Environment: