[FIX] bus: Bus unavailable error in multi process mode

Starting the Odoo server with more than one worker results in repeated
"Bus unavailable" exceptions in the server log.

This seems related to the change made at
https://github.com/odoo/odoo/commit/a2ed3d3d5bdb6025a1ba14ad557a115a86413e65



 Investigation shows the the bus model file is loaded before gevented
 mode is started, and thus the wroker won't have the ImDispach
 available.

closes odoo/odoo#111352

Signed-off-by: Stockbauer Matthieu (tsm) <tsm@odoo.com>

addons/bus/models/bus.py

@@ -194,7 +194,7 @@ class ImDispatch(object):
         self.started = True
         return self
 
-dispatch = None
-if not odoo.multi_process or odoo.evented:
-    # We only use the event dispatcher in threaded and gevent mode
-    dispatch = ImDispatch()
+# Partially undo a2ed3d3d5bdb6025a1ba14ad557a115a86413e65
+# IMDispatch has a lazy start, so we could initialize it anyway
+# And this avoids the Bus unavailable error messages
+dispatch = ImDispatch()