Once restrict height, always restrict height

[cdemirer]

Using Godot 4.6.

When you enable the "restrict height" option in a modifier, it stays that way in-game and for scene save.

Repro:

• Open demo scene showcase.tscn.
• Select Mushrooms.
• Enable "restrict height" in the Create Inside (Grid) modifier.
• Run scene (maybe optional?).
• Disable "restrict height".
• Run scene. Observe that the height is still restricted in-game.
• Save and reload the scene. Observe that the height is still restricted.