Use template tileset in template challenges

[wjt]

In #1080 we added a template tileset to scenes/quests/story_quests/template/template_tileset. But it is not used in the template challenges.

Should we change that, and rebuild those levels to use the template tileset? Then, perhaps as a follow-up, make the template instantiation tool update the duplicated scenes to use the duplicate?

[manuq]

I remember asking the Learning team and the answer was no. But maybe we want to revisit it?