"Thumbstick Opacity" setting does not work

Summary:
A new "Thumbstick Opacity" setting was added for touch controls, but it does not work.

Steps to Reproduce:

1. Launch Minecraft on a touch device
2. Create a new world
3. Tap and hold on the screen
4. Observe the opacity of the thumbstick
5. Go to Settings > Touch
6. Move the "Thumbstick Opacity" slider to 5%
7. Tap and hold on the screen
8. Observe the opacity of the thumbstick

Observed Results:
The opacity of the thumbstick is the same as before.

Expected Results:
The opacity of the thumbstick should be lower.