Remove `m_e_stop_listener` from `token_mgr`
This is a leftover from the previous commit. Also further
improved E-Stop handling. While `token_mgr::m_safe_state` is `true`,
`update()` doesnt do something. If `update()` gets called while in
safe state, `m_update_req` is set to `true`. When the system leaves
its safe state and `m_update_req` is `true`, then `update()` gets
called once.