shimv2: cancel monitor before stopping sandbox

So that we don't trigger sandbox watcher on our own.

Signed-off-by: Peng Tao <bergwolf@hyper.sh>

containerd-shim-v2/wait.go

@@ -53,6 +53,10 @@ func wait(s *service, c *container, execID string) (int32, error) {
 		// sandbox.
 
 		if c.cType.IsSandbox() {
+			// cancel watcher
+			if s.monitor != nil {
+				s.monitor <- nil
+			}
 			if err = s.sandbox.Stop(true); err != nil {
 				logrus.WithField("sandbox", s.sandbox.ID()).Error("failed to stop sandbox")
 			}