cri,nri: block NRI plugin sync. during event processing.

Block the synchronization of registering NRI plugins during
CRI events to avoid the plugin ending up in an inconsistent
starting state after initial sync (missing pods, containers
or missed events for some pods or containers).

Signed-off-by: Krisztian Litkey <krisztian.litkey@intel.com>

internal/cri/server/sandbox_remove.go

@@ -44,6 +44,9 @@ func (c *criService) RemovePodSandbox(ctx context.Context, r *runtime.RemovePodS
 			r.GetPodSandboxId())
 		return &runtime.RemovePodSandboxResponse{}, nil
 	}
+
+	defer c.nri.BlockPluginSync().Unblock()
+
 	// Use the full sandbox id.
 	id := sandbox.ID
 	span.SetAttributes(tracing.Attribute("sandbox.id", id))