Providing customID but not username in KongConsumer does not work

[randmonkey]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

From FTI-6236.
The customer uses a KongConsumer with empty username and non-empty custom_id, ans see panic in KIC.

Expected Behavior

KongConsumer with non empty custom_id but empty username should also work.

Steps To Reproduce

1. Setup a Kong Env using KIC
2. Attempt to apply a KongConsumer with no username, just a custom_id
3. Observe KIC logs, it will Crash Loop shortly after

Kong Ingress Controller version

3.3.1

Kubernetes version

No response

Anything else?

No response