Drop-downs show no highlight when using keyboard navigation

### What Happened?

This might be an issue with the GUI toolkit and not with the power settings. However, I didn't know which repo to add the issue to. I'm happy to re-open it somewhere else if you tell me where.

The issue is a keyboard navigation/a11y one. I tried to use elementary OS without a mouse and while it works very well I hit this issue in the power settings: the drop-downs for sleep timeouts can be opened with the keyboard only but there is no highlight when I use the up/down cursor keys. I can confirm an option blindly so the GUI knows the active item. It just doesn't display this in any way. If I reopen the drop-down and press the cursor key down once and hit enter, the selected option is *not* the next one in the list which leads me to believe that the drop-down starts up with the first item selected (but not highlighted) every time it's opened.

(related bug: my locale is German but the yellow text about energy use is not translated. Where do I submit a repoprt for this or where can I help to translate this?)

### Steps to Reproduce

1. go to power settings page
2. use tab and cursor keys to navigate to a drop-down (e.g. the monitor timeout one) and open it using the cursor keys (spacebar might work as well but I don't remember this correctly)
3. use cursor keys up and down, no highlight is shown to indicate the active item
4. hit enter key
5. an option is selected demonstrating that even though there was no highlight, it was possible to select an item from the drop-down.

### Expected Behavior

active item is highlighted (like it is when selecting one with the mouse)

### OS Version

8.x (Circe)

### OS Architecture

amd64 (on most hardwares)

### Session Type

Secure Session (Wayland, This is the default)

### Software Version

Latest release (I have run all updates)

### Log Output

```shell

```

### Hardware Info

_No response_