Can't override `_to_string` of `InputEventAction`

Tested versions

4.4.1, 4.5

System information

Linux

Issue description

Can't override _to_string of InputEventAction because the to_string is already override in Godot source code:
https://github.com/godotengine/godot/blob/2dd26a027a99633231184616d4dd287bbdd1c0a3/core/input/input_event.h#L496
https://github.com/godotengine/godot/blob/2dd26a027a99633231184616d4dd287bbdd1c0a3/core/input/input_event.cpp#L1657-L1660

This issue exists in both gdscript and gdextension.

Steps to reproduce

extends Node2D

class InputEventA extends InputEventAction:
	func _to_string() -> String:
		return "A"

func _ready() -> void:
	print(self.to_string())
	var a := InputEventA.new()
	print(a.to_string())

func _to_string() -> String:
	return "This Node"

This prints:

This Node
InputEventAction: action="", pressed=false

Minimal reproduction project (MRP)

N/A

Start with core/input/input_event.h around line 496 and core/input/input_event.cpp around lines 1657-1660, then reproduce the behavior with the GDScript example from the issue. Check how InputEventAction string conversion interacts with subclass overrides in GDScript and GDExtension; done means the override is honored in both cases and the behavior is covered by tests.