Remove -nodeport discovery configmap

[nightkr]

It's redundant now that #443 (24.11) brings first-class NodePort support. The primary discovery CM will now automatically adapt to the selected ListenerClass.

Deprecation schedule:

• Starting with 24.11, it is identical to the primary discovery CM (Migrate kafka-operator to use listener-operator for exposing brokers #443)
• In 25.3, it is officially deprecated (Deprecate -nodeport discovery ConfigMap #813)
• In 25.3+1, it will be removed completely

Users are encouraged to replace all uses with the primary discovery CM after upgrading to 24.11.

[nightkr]

Looks like we never actually deprecated this properly back in 24.11. I would propose rescheduling it for deprecation in 25.3 and removal in 25.3+1.

[lfrancke]

Makes sense. Thanks for catching it. I agree with the proposal.

[nightkr]

Marking this as "done" since #813 is merged, but we shouldn't close it before it's removed as well.