edit prediction: Fix popover positioning when placed above edit (#23902)

Fixes an off-by-one error when the popover was placed above the edit:
<img width="688" alt="Screenshot 2025-01-30 at 11 59 14"
src="https://github.com/user-attachments/assets/938a6626-3f4d-4566-b68c-89b14d48b68d"
/>


Release Notes:

- N/A
5e210c083fBennet Bo Fenner committed on 1/30/2025, 11:16:56 AM· committed by GitHubparent5e449c8
1 file changedLine totals unavailable