[skip ci]Fix golint error for Stop in QueryNode (#10306)

Signed-off-by: cai.zhang <cai.zhang@zilliz.com>

internal/distributed/querynode/client/client.go

@@ -172,6 +172,7 @@ func (c *Client) Start() error {
 	return nil
 }
 
+// Stop stops QueryNode's grpc client server.
 func (c *Client) Stop() error {
 	c.cancel()
 	c.grpcClientMtx.Lock()