Clean up any more V(numeric) for log levels

[kfswain]

We created: https://github.com/kubernetes-sigs/gateway-api-inference-extension/blob/main/pkg/ext-proc/util/logging/logging_const.go

To more easily standardize our log levels. We should remove any more V(int), and either use an existing level, or define a new one with reasonable justification.

[ahg-g]

duplicate #251 ?

[tchap]

This is actually handled as a side effect in #330

[tchap]

This can be now closed as #330 is merged.