bug(MatDialog): Blocked aria-hidden error when hasBackdrop is false

### Description

I am launching a dialog that has a MatDialogConfig property of hasBackdrop = false. Doing so seems to still attach a aria-hidden="true" property to DOM elements that are siblings to the cdk overlay container. This in turn seems to cause a console error of "Blocked aria-hidden on..." when interacting with DOM elements that live underneath one of those sibling elements while the dialog is open. The console error seems to be intermittent.

### Reproduction

stackblitz link: https://stackblitz.com/edit/ue8xe5
1. launch dialog
2. while dialog is open click into the text box
3. console error should appear (can be intermittent)

### Expected Behavior

I wouldn't expect the console error to occur

### Actual Behavior

Console error occurs:
Blocked aria-hidden on a element because the element that just received focus must not be hidden from assistive technology users. Avoid using aria-hidden on a focused element or its ancestor. Consider using the inert attribute instead, which will also prevent focus. For more details, see the aria-hidden section of the WAI-ARIA specification at https://w3c.github.io/aria/#aria-hidden.

### Environment

- Angular: 18.0.1
- CDK/Material: 18.1.4
- Browser(s): Chrome
- Operating System (e.g. Windows, macOS, Ubuntu): Windows

Start with the linked StackBlitz reproduction and inspect MatDialogConfig.hasBackdrop=false while following the dialog's aria-hidden behavior. Reproduce the intermittent Chrome console error by focusing the text box while the dialog is open; done means the error no longer occurs and the expected focus behavior is preserved.

Written by the indexing model from the issue text.