Since [1], the websocket worker is started when a transient thread is added to the mail store. This occurs because this PR introduced a call to the `addChannel` method of the bus service when the current user was not member of the thread. Since transient threads are not yet created, they have a partial state that does not necessarily include channel members hence the impression that the current user is not member of the channel. This PR prevent starting the bus service for transient threads. [1]: https://github.com/odoo/odoo/pull/146800 closes odoo/odoo#153000 Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>