Update slightly obsolete / deprecated client library references in KNE

[kraney]

remove direct controller-runtime dependency and modernize CRD clients

Refactor Nokia node implementation and Metallb / Meshnet clientsets to use
standard client-go dynamic clients and static TypeMeta definitions, completely
eliminating sigs.k8s.io/controller-runtime as a direct dependency.

Summary of changes:
- topo/node/nokia/nokia.go:
  - Replace controller-runtime Client (ctrlclient.New, c.Create, c.Delete)
    with dynamic.NewForConfig and c.Resource(srlGVR).Namespace(ns).Create/Delete.
  - Convert srlinuxv1.Srlinux resources to unstructured.Unstructured via
    runtime.DefaultUnstructuredConverter, consistent with other KNE nodes.
  - Remove newSrlinuxClientWithSchema and controller-runtime imports.
- api/metallb/clientset/v1beta1:
  - In ipaddresspool.go and l2advertisement.go, assign TypeMeta statically
    (Kind and metallbv1.GroupVersion) instead of calling apiutil.GVKForObject.
  - In client.go, remove metallbv1.AddToScheme(Scheme) from init() to avoid
    package initialization side-effects.
  - Remove unused controller-runtime/pkg/client/apiutil imports.
- third_party/meshnet/api/clientset/v1beta1/topology.go:
  - Assign TypeMeta statically (Kind: "Topology", topologyv1.SchemeGroupVersion)
    instead of calling apiutil.GVKForObject.
  - Remove unused apiutil import.
- go.mod & go.sum:
  - Remove sigs.k8s.io/controller-runtime as a direct dependency.
  
Also:
Update K8s nodeaffinity references

These are no longer in beta (for some time) use the official reference

Rationale:
- Simplifies KNE dependency tree by relying exclusively on client-go and
  apimachinery rather than pulling in the full controller-runtime framework.
- Standardizes CRD creation and deletion across all node implementations.
- Avoids runtime reflection and scheme registration errors during clientset
  initialization.

Note for googlers - see b/540005636 and cl/968544355