agent: Kill the all the container processes of the same cgroup

Otherwise the container process might leak and cause an unclean exit

Fixes: #3913

Signed-off-by: Feng Wang <feng.wang@databricks.com>

src/runtime/pkg/containerd-shim-v2/service.go

@@ -776,6 +776,8 @@ func (s *service) Kill(ctx context.Context, r *taskAPI.KillRequest) (_ *ptypes.E
 			return empty, errors.New("The exec process does not exist")
 		}
 		processStatus = execs.status
+	} else {
+		r.All = true
 	}
 
 	// According to CRI specs, kubelet will call StopPodSandbox()