updates for landing zone sign sprites (#3180)

# About the pull request

Cleans up the palettes on the landing zone sign sprites and gives them a
fresh coat of paint (or blood). Not something most people will notice I
think but it's something I've been wanting to do.


# Explain why it's good for the game

gradients ugly


# Before and After
<details>
<summary>Click to see sprites</summary>


![osudodajs2](https://user-images.githubusercontent.com/106241650/235265980-e622b7da-8f79-4920-ba27-97d704c65550.gif)


![beforenafter](https://user-images.githubusercontent.com/106241650/235266004-0e46a574-9262-445f-98d9-4b19aa53a8fb.png)

</details>


# Changelog

:cl:
imageadd: new sprites for landing zone signs
imagedel: deleted old landing zone signs
/:cl: