Custom shortcuts Shift+Alt+I for ui_text_caret_line_end not working

### Tested versions

Reproducible in Godot 4.2.1 and master-4a0160241fd0c1e874e297f6b08676cf0761e5e8.

### System information

Windows 10 - Godot v4.2.1 Vulkan 1.3.277 - Forward+

### Issue description

I was learning Godot for game develop and try to add a custom shortcuts Shift+Alt+I to move cursor to line end. After I add the shortcuts in editor settings, I just found it is not working.

I also tried to build the latest Godot source code (HEAD at commit 4a0160241fd0c1e874e297f6b08676cf0761e5e8) and it's still not working.

Then I just dig into the Godot source code, and found (maybe not correct) that the shift key is unset when checking the caret_line_end action.

Is this the bug? Or there is just another way to solve this?

### Steps to reproduce

Open or create any project.
Open editor settings and add shortcuts Shift+Alt+I for ui_text_caret_line_end.
Open any script and put the caret in the middle of a sentence.
Press Shift+Alt+I, expect caret moved to line end, but found nothing happended

### Minimal reproduction project (MRP)

[foo.zip](https://github.com/godotengine/godot/files/15078359/foo.zip)
Just an empty project with a script attached to root node is enough.