Issue Description:
A namespace on Dev cluster was stuck in Terminating state.
Inspection revealed that it was stuck because of several Knative Brokers existed in the namespace when it was terminated by our RHOSE operator.

As temporary solution the operator shouldn't delete namespaces if they contain Knative Brokers.

A refactoring was suggested by Rob:
I think if we change our namespace strategy to be created for each Bridge rather than per-customer it will solve a couple of problems here:

1. Make it much easier to find the namespace for a particular Bridge e.g ob-$bridge_id is the namespace
2. The namespace can be deleted when the Bridge is deleted, rather than at a scheduled point in time

Acceptance Criteria:
Namespace is not deleted by operator when Knative Broker is present in namespace

Out of Scope:

Additional Information: