New assigned shortcut shift + a doesn't work

### Tested versions

I've tried it and got the same results in
godot 4.3 (NET)
godot 4.4 beta 1 (NET)
other versions I don't know

### System information

Windows 11

### Issue description

I think this is not reported yet? sorry if I'm wrong (and could be a me issue maybe? tho I've tried it on two devices)

I've tried to set a new shortcut shift + a for adding a child node and it doesn't work
I've also reassign and tested with a different shortcut eg. Ctrl + Shift + N and this works


### Steps to reproduce

set a new shortcut for adding a child node
Ctrl+A -> Shift+A

### Minimal reproduction project (MRP)

N/A

Reproduce the shortcut assignment in the Godot editor on Windows 11 using the Add Child Node action, changing Ctrl+A to Shift+A and comparing it with Ctrl+Shift+N. Trace the editor's shortcut handling for this action and verify that Shift+A invokes Add Child Node after reassignment without breaking the working alternative.

Written by the indexing model from the issue text.