kubernetes: trim client-go dependency surface

Replace the full generated clientset and global Kubernetes scheme
with a small local REST client layer and minimal scheme registration.

This keeps the existing kubeconfig/auth and remote exec behavior while
significantly reducing the linked and vendored Kubernetes dependency set.

Signed-off-by: Tonis Tiigi <tonistiigi@gmail.com>

go.mod

@@ -113,7 +113,6 @@ require (
 	github.com/digitorus/timestamp v0.0.0-20231217203849-220c5c2851b7 // indirect
 	github.com/docker/docker-credential-helpers v0.9.5 // indirect
 	github.com/docker/go-connections v0.6.0 // indirect
-	github.com/emicklei/go-restful/v3 v3.13.0 // indirect
 	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/fvbommel/sortorder v1.1.0 // indirect
 	github.com/fxamacker/cbor/v2 v2.9.0 // indirect
@@ -147,7 +146,6 @@ require (
 	github.com/gogo/protobuf v1.3.2 // indirect
 	github.com/golang/protobuf v1.5.4 // indirect
 	github.com/google/certificate-transparency-go v1.3.2 // indirect
-	github.com/google/gnostic-models v0.7.0 // indirect
 	github.com/google/go-cmp v0.7.0 // indirect
 	github.com/google/go-containerregistry v0.20.7 // indirect
 	github.com/gorilla/websocket v1.5.4-0.20250319132907-e064f32e3674 // indirect
@@ -232,11 +230,9 @@ require (
 	golang.org/x/time v0.14.0 // indirect
 	golang.org/x/tools v0.41.0 // indirect
 	google.golang.org/genproto/googleapis/api v0.0.0-20251202230838-ff82c1b0f217 // indirect
-	gopkg.in/evanphx/json-patch.v4 v4.12.0 // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 	k8s.io/klog/v2 v2.130.1 // indirect
-	k8s.io/kube-openapi v0.0.0-20250710124328-f3f2b991d03b // indirect
 	k8s.io/utils v0.0.0-20250604170112-4c0f3b243397 // indirect
 	sigs.k8s.io/json v0.0.0-20241014173422-cfa47c3a1cc8 // indirect
 	sigs.k8s.io/randfill v1.0.0 // indirect