Remove serve_static_files(assets) from test config.
Remove serve_static_files(assets) from test config.

Default value of config.serve_static_files(assets) is `true`.

y-yagi/garage,kenchan0130/garage,y-yagi/garage,takashi/garage,takashi/garage,luvtechno/garage,takashi/garage,cookpad/garage,cookpad/garage,kenchan0130/garage,luvtechno/garage,taiki45/garage,taiki45/garage,cookpad/garage,cookpad/garage,y-yagi/garage,kenchan0130/garage,taiki45/garage,luvtechno/garage