`_is_in_input_hotzone` and `_is_in_output_hotzone` still refers to old theme constants

[williamchange]

Your Godot version:
4.4.1

Issue description:
Both port_grab_distance_horizontal and port_grab_distance_vertical has been removed and the relevant theme constants are now port_hotzone_inner_extent and port_hotzone_outer_extent.

Description and sample code for both these functions(_is_in_input_hotzone and _is_in_output_hotzone) are still referring to the old variables.

URL to the documentation page:
https://docs.godotengine.org/en/stable/classes/class_graphedit.html