setup lxd: standalone profile uses the default port, not -addr's

pkgproxyctl setup lxd without -project renders the pkgproxy profile with defaultListenAddr's port instead of the port from -addr (or from the running daemon's /v1/info). So when pkgproxy listens on a port other than 3142, GOPROXY and the proxy settings in the profile name the wrong port. The project variant (-project, setup snapcraft) uses the right port. Found while auditing the help text. Fix the render call and add a canned-output test with a non-default -addr.