Fixes asteroid exoplanet turf lighting (#21599)

Replaces pixel_x/pixel_y adjustment for asteroid turfs with transform
method. This is the same method /tg/ uses for their turfs equalivent to
our asteroid turfs

Fixes #21587

## Images

<details><summary>Before:</summary>
<p>

<img width="997" height="981" alt="Screenshot_2"
src="https://github.com/user-attachments/assets/60e8c95e-574c-4aca-b7b6-cc2e94812823"
/>

</p>
</details> 

<details><summary>After:</summary>
<p>

<img width="998" height="984" alt="Screenshot_1"
src="https://github.com/user-attachments/assets/e49aa7d4-27e0-4c56-84d9-6002a768f621"
/>

</p>
</details>

code/modules/overmap/exoplanets/decor/turfs/snow.dm

@@ -16,8 +16,9 @@
 
 /turf/simulated/floor/exoplanet/snow/Initialize()
 	. = ..()
-	pixel_x = -4
-	pixel_y = -4
+	var/matrix/M = new
+	M.Translate(-4, -4)
+	transform = M
 	icon_state = pick("snow[rand(1,2)]","snow0","snow0")
 	QUEUE_SMOOTH_NEIGHBORS(src)
 	QUEUE_SMOOTH(src)