[FIX] bus: remove simple notification service from frontend

Since [1], the notifications of type `simple_notification` are
handled by a service in the bus module.

Before [2] those notifications were handled by the messaging handler
which was only loaded in the backend.

This commit restores the previous behavior as the simple notification
service starts the bus service which result in the websocket worker being
loaded why it should be done lazily (i.e. only when the livechat is used).

[1]: https://github.com/odoo/odoo/pull/119243
[2]: https://github.com/odoo/odoo/pull/110188

closes odoo/odoo#122266

Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>

addons/bus/__manifest__.py

@@ -20,6 +20,7 @@
             'bus/static/src/*.js',
             'bus/static/src/services/**/*.js',
             ('remove', 'bus/static/src/services/assets_watchdog_service.js'),
+            ('remove', 'bus/static/src/simple_notification_service.js'),
             'bus/static/src/workers/websocket_worker.js',
             'bus/static/src/workers/websocket_worker_utils.js',
         ],