server: correctly fill ctr termination reason

This patch fixes all port forwarding e2e tests. Those tests were
specifically looking for a termination reason to say that a given
container has finished running. CRI-O wasn't actually returning any
reason field for an exited container.

-> https://github.com/kubernetes/kubernetes/blob/master/test/e2e/portforward.go#L116
   -> https://github.com/kubernetes/kubernetes/blob/master/test/utils/conditions.go#L97

Signed-off-by: Antonio Murdaca <runcom@redhat.com>

server/container_status.go

@@ -98,8 +98,13 @@ func (s *Server) ContainerStatus(ctx context.Context, req *pb.ContainerStatusReq
 		finished := cState.Finished.UnixNano()
 		resp.Status.FinishedAt = finished
 		resp.Status.ExitCode = cState.ExitCode
-		if cState.OOMKilled {
+		switch {
+		case cState.OOMKilled:
 			resp.Status.Reason = "OOMKilled"
+		case cState.ExitCode == 0:
+			resp.Status.Reason = "Completed"
+		default:
+			resp.Status.Reason = "Error"
 		}
 	}