### Tested versions

- First reproducible in: v4.2.dev5.official [e3e2528ba]
- Reproducible in: v4.2.stable.official [46dc27791], v4.2.dev5.official [e3e2528ba], v4.2.dev6.official [57a6813bb]
- Not reproducible in: v4.1.3.stable.official [f06b6836a], v4.2.dev1.official [0c2144da9], v4.2.dev2.official [da81ca62a], v4.2.dev3.official [013e8e3af], v4.2.dev4.official [549fcce5f]

### System information

Godot v4.2.stable - Windows 10.0.19045 - Vulkan (Forward+) - dedicated NVIDIA GeForce GTX 1080 (NVIDIA; 31.0.15.4617) - Intel(R) Core(TM) i5-8600K CPU @ 3.60GHz (6 Threads)

### Issue description

The `TileSet` `set_occlusion_layer_light_mask` method does not properly update the `TileSet`'s light mask, causing shadows to still be cast by the `TileSet` even when the light mask is changed using the method to a mask different from a given light source (or even an empty light mask). In v4.1.3.stable.official [f06b6836a] this method was working properly.

### Steps to reproduce

- Download and open the `MRPSetOcclusionLayerTileSet_4.2-stable` project folder using one of the reproducible Godot versions noted above.
- Run the project, and press the spacebar key. This will toggle the occlusion layer light mask value of the on-screen `TileMap`'s `TileSet` occlusion light mask between 0 and 1. You will see that the `TileMap` still casts shadows regardless of the new value of its `TileSets`'s occlusion layer light mask.

### Minimal reproduction project (MRP)

[MRPSetOcclusionLayerTileSetBug.zip](https://github.com/godotengine/godot/files/13592741/MRPSetOcclusionLayerTileSetBug.zip)

TileData *tile_data = atlas_source->get_tile_data(cell.get_atlas_coords(), cell.alternative_tile);
				if (tile_data && tile_data->get_terrain_set() == p_terrain_set) {
					current_pattern = tile_data->get_terrains_pattern();
				}
			}
		}
		TileSet::TerrainsPattern pattern = _get_best_terrain_pattern_for_constraints(p_terrain_set, coords, constraints, current_pattern);
		
		RBSet<TerrainConstraint> new_constraints = _get_terrain_constraints_from_added_pattern(coords, p_terrain_set, pattern);
		for (const TerrainConstraint &E_constraint : new_constraints) {
			if (constraints.has(E_constraint)) {
				constraints.erase(E_constraint);
			}
			TerrainConstraint c = E_constraint;
			c.set_priority(5);
			constraints.insert(c);
		}
		output[coords] = pattern;
	}
	return output;
}
HashMap<Vector2i, TileSet::TerrainsPattern> TileMapLayer::terrain_fill_connect(const Vector<Vector2i> &p_coords_array, int p_terrain_set, int p_terrain, bool p_ignore_empty_terrains) {
	HashMap<Vector2i, TileSet::TerrainsPattern> output;
	const Ref<TileSet> &tile_set = tile_map_node->get_tileset();
	ERR_FAIL_COND_V(!tile_set.is_valid(), output);
	ERR_FAIL_INDEX_V(p_terrain_set, tile_set->get_terrain_sets_count(), output);
	
	Vector<Vector2i> can_modify_list;
	RBSet<Vector2i> can_modify_set;