jobsite/builder: no caching for osbuild.

As builders are not re-used caching has no use and can likely only
lead to disk-size issues. This can be re-enabled when we have an
outside-of-the-builder cache.

cmd/osbuild-jobsite-builder/main.go

@@ -240,8 +240,7 @@ func (builder *Builder) HandleBuild(w http.ResponseWriter, r *http.Request) erro
 
 	args := []string{
 		"--store", path.Join(argBuildPath, "store"),
-		"--cache-max-size", "unlimited",
-		"--checkpoint", "*",
+		"--cache-max-size", "0",
 		"--output-directory", path.Join(argBuildPath, "export"),
 	}