Remove !nodes condition from gTorCircuitPanel._updateCurrentBrowser

nodes is always an array, so the check is redundant and the comment is misleading: https://gitlab.torproject.org/tpo/applications/tor-browser/-/blob/0629814fc1ab65f06306868f736711e415cf5519/browser/components/torcircuit/content/torCircuitPanel.js#L318-319