fix(helm): disable controller metrics when bindAddress is empty or 0 (#2785)

## Summary

Fixes an issue where the metrics port was still rendered as
`containerPort: 0` when metrics were disabled using `bindAddress: "0"`
or an empty `bindAddress`.

The deployment was checking `.Values.controller.metrics.enabled`
directly, while the other metrics-related resources use the
`kagent.controller.metricsEnabled` helper.

## Fix

Use the same helper for the metrics port:

```diff
- {{- if .Values.controller.metrics.enabled }}
+ {{- if include "kagent.controller.metricsEnabled" . }}
```

This keeps all metrics-related resources consistent and does not change
the default `:8443` behavior.

## Tests

* Fixed the existing port assertions to use `any: true`.
* Added coverage for an empty `bindAddress`.
* `helm unittest helm/kagent`: **284 passed, 21 suites**
* Verified with `helm template` that the port is omitted for `0` and
`""`, and remains `8443` by default.

Fixes #2736

Signed-off-by: Gous0786 <gousalam0786@gmail.com>