Pause menu background is completely transparent

The pause menu used to have a black tint. In Java Edition, the overlaid background is handled as a texture file that can be configured via resource packs.

Steps to reproduce:

1. Enable game pause in Settings -> General -> General -> Pause
2. Pause the game

Observed result:
The pause menu background is completely transparent.

Expected result:
The pause menu background is not completely transparent and has a black/gray tint, like in Java Edition.