[consolidated] Dispatcher deployment readonly

[pierDipi]

Problem
The dispatcher deployment updates the status of the KafkaChannel and every update needs to be done by the leader and replicas don't receive informer updates, since we use only ReconcileKind.
This behavior breaks dispatcher horizontal scalability and if there are multiple replicas of a dispatcher the information that is in the status isn't really accurate since it reflects the status of the leader only.

In knative/eventing-contrib#1446 we had a discussion on how we can solve this problem.

There are other problems related to updating the status in the dispatcher like in knative/eventing#4280.

Persona:
Which persona is this feature for?
*

Exit Criteria
One of the solutions outlined in the linked discussion.

Time Estimate (optional):
How many developer-days do you think this may take to resolve?
1

Additional context (optional)

• Discussion: Fix TestBrokerRedelivery knative/eventing-contrib#1446 (comment)