Running the bus garbage collector synchronously during the handling of a
request can stall the request for a very long time.
Instead, we add this step to the existing auto-vacuum scheduled job that
handles this kind of housecleaning. It brings another interesting bonus:
it can be scheduled outside of peak hours, which will avoid blocking other
bus-related transactions (the GC deletes a lot of rows and takes a lot
of exclusive locks in the database)
closesodoo/odoo#28326