Revert "Move time.Sleep call in turbotunnel test"

This reverts commit 4497d68d6f.

common/turbotunnel/queuepacketconn_test.go

@@ -208,16 +208,14 @@ func TestQueuePacketConnWriteToKCP(t *testing.T) {
 			panic(err)
 		}
 
-		// A sleep after the Write makes buffer reuse more likely, and is needed
-		// to allow time for flushing all bytes written to the connection before close.
-		// This is not guaranteed by kcp-go. See https://github.com/xtaci/kcp-go/issues/273
-		time.Sleep(100 * time.Millisecond)
-
 		err = conn.Close()
 		if err != nil {
 			panic(err)
 		}
 
+		// A sleep after the Write makes buffer reuse more likely.
+		time.Sleep(100 * time.Millisecond)
+
 		if len(transcript.Transcript) == 0 {
 			panic("empty transcript")
 		}