Disabled item cooldown overlay renders opaque in front of effect icons

This completely blocks MC-270306, since disabled item cooldown overlay renders in front of effect icons in inventory. However, now the overlay is opaque and renders the part blocked by the icons when the icons are behind it, whereas most other GUIs don't render like it.

Steps to reproduce:

1. Get this item:

   /give @p minecraft:wind_charge[minecraft:use_cooldown={seconds:100}]

2. Use it

3. Hold it in front of the effects icons off to the right side of the inventory