[Bug]: Modal overlays do not always close on Esc

### Code of conduct

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

### Impacted component(s)

sp-overlay

### Library version

1.7.0

### Expected behavior

Pressing Esc when a modal overlay is opened should close it.

### Actual behavior

Pressing Esc does not always close the topmost modal overlay.

### Screenshots

_No response_

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

_No response_

### How can we reproduce this issue?

1. Go to https://stackblitz.com/edit/vitejs-vite-6qhlkpyu?file=src%2Fmy-element.ts
2. Click on the button
3. Hit Esc

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

_No response_

### Severity

SEV 2

### Logs taken while reproducing problem

_No response_

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

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

Start with the linked StackBlitz reproduction at src/my-element.ts and inspect the sp-overlay component involved in the Esc interaction. Reproduce the failure with a modal overlay and confirm that pressing Esc consistently closes the topmost overlay; use the reproduction to verify the behavior after the change.

Written by the indexing model from the issue text.