Limit kafka controller permissions

**Problem**
I have a security requirement to limit the permissions of the kafka controller that created by the `knative-eventing` operator to access to secret only in specific namespaces.

**[Persona:](https://github.com/knative/eventing/blob/main/docs/personas.md)**
Which persona is this feature for?

System Operator

**Exit Criteria**
A measurable (binary) test that would indicate that the problem has been resolved.

to be able to limit the permissions to read secrets for specific namespaces

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

**Additional context (optional)**

The issue names the knative-eventing operator and its Kafka controller, but no files or tests. Start by locating the operator's Kafka controller permissions and how secret access is configured across namespaces. Done means a measurable test confirms secret reads can be limited to specified namespaces.

Written by the indexing model from the issue text.