Saving settings moves/looses focus to Startup item

### Windows Terminal version

1.17.11461.0

### Windows build number

10.0.19045.2965

### Other Software

_No response_

### Steps to reproduce

Click Save button in Settings dialog (for any profile, nested item)

### Expected Behavior

Focus won't be lost/moved; current settings pane/context won't be changed/lost.

### Actual Behavior

Focus switches to Startup item, quiting some (distant) profile settings pane, unexpectedly changing context.

Start by reproducing the focus change in the Windows Terminal Settings dialog using the reported version and steps. Trace what happens when Save is clicked from a nested profile setting; done means focus and the current settings pane or context remain unchanged.

Written by the indexing model from the issue text.