I have always seen them refered to as drill uniforms, although I am no expert. He also had a picture of his great uncle in combat his uniform in the same post.
German soldiers - Album on Imgur
I also noticed that in the photo where they have smles they aren't carrying ammunition or anything else to suggest they are actively engaged in anything aside from drill, although that's just my 2¢. Mostly just wanted to share the photo as it's the only one I'm aware of.
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