Fix look_at_from_position() usage in Squash the Creeps (3D)

[Calinou]

• Demos counterpart of Fix look_at_from_position() usage in Your first 3D game tutorial godot-docs#10666.

The mob's orientation was previously shifted according to the player's height, which could lead to collision and movement issues that were difficult to diagnose.

[gabriele2000]

In my modest opinion, as a user and someone with a very small (for now) background on programming, I'd like to propose a change.

The following changed code

func initialize(start_position, player_position):
	# Ignore the player's height, so that the mob's orientation is not slightly
	# shifted if the mob spawns while the player is jumping.
	var target = Vector3(player_position.x, start_position.y, player_position.z)
	look_at_from_position(start_position, target, Vector3.UP)

could be just

func initialize(start_position, player_position):
	# Ignore the player's height, so that the mob's orientation is not slightly
	# shifted if the mob spawns while the player is jumping.
        # start_position.y could also be written as 0.0
	player_position = Vector3(player_position.x, start_position.y, player_position.z)
	look_at_from_position(start_position, player_position, Vector3.UP)

player_position has been already declared inside func, now we just need to overwrite the player_position.y value then process the overwrited value.
No need to declare a variable, let alone a new one, just for a small correction.

[aaronfranke]

Needs a rebase.

@gabriele2000 Modifying function parameters is considered a bad practice by some, so I wouldn't encourage it in official demos, even though it would work fine either way and potentially use ever-so-slightly less memory.

[aaronfranke]

I resolved the conflicts, this is good to go!