[Bug]: Submenus do not open on hover after hovering over another menu item with a submenu

### Code of conduct

- [x] I agree to follow this project's code of conduct.

### Impacted component(s)

sp-menu-item

### Library version

1.9.0

### Expected behavior

Submenus should open when their menu item is hovered.

### Actual behavior

Submenus do not open.

### Screenshots

https://github.com/user-attachments/assets/b12d9ec1-9e88-474f-a6b2-2dc05af08fab

### What browsers are you seeing the problem in?

_No response_

### How can we reproduce this issue?

1. Go to https://opensource.adobe.com/spectrum-web-components/storybook/index.html?path=/story/menu-submenu--submenu&globals=system:spectrum-two
2. Hover over a menu item with a submenu to open it
3. Hover over the other menu item with a submenu
4. Observe how neither submenu can open

### Sample code or abstract reproduction which illustrates the problem

_No response_

### Severity

SEV 1

### Logs taken while reproducing problem

_No response_

### Would you like to track this issue in Jira?

- [x] Yes, please tell me the ticket number!