Remove usage of ocstatus package

This changes the tracing package to accept an error on SetStatus, which
is really what we always want anyway.
This also decouples the trace package from opencensus.

providers/mock/mock.go

@@ -10,7 +10,6 @@ import (
 	"strings"
 	"time"
 
-	"github.com/cpuguy83/strongerrors/status/ocstatus"
 	"github.com/virtual-kubelet/virtual-kubelet/errdefs"
 	"github.com/virtual-kubelet/virtual-kubelet/log"
 	"github.com/virtual-kubelet/virtual-kubelet/trace"
@@ -201,7 +200,7 @@ func (p *MockProvider) DeletePod(ctx context.Context, pod *v1.Pod) (err error) {
 func (p *MockProvider) GetPod(ctx context.Context, namespace, name string) (pod *v1.Pod, err error) {
 	ctx, span := trace.StartSpan(ctx, "GetPod")
 	defer func() {
-		span.SetStatus(ocstatus.FromError(err))
+		span.SetStatus(err)
 		span.End()
 	}()