Remove remote broadcasting of Updating events

Description

CatalogEventBroadcaster sends remote events for the EventContext's Updating events (e.g. RelationUpdating). This is pointless.
The purpose of the Updating events is to allow reaction to the change, e.g. cancelling parts of it, before the change gets saved. This is impossible for a remote party, which renders the remote replication of the event moot. So it is just unnecessary noise on the remote event channel. The final modification, which may indeed be interesting to a remote party, is described by the following Updated event.