[#4477]Fix GoAway issue in Http2 after many requests timeout

[liubao68]

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[yanghao605]

这个改法是判断连接是否closed来决定服务端是否调用end方法，推送数据，这里跳过end方法是否会对服务端的连接产生影响？

[liubao68]

这个改法是判断连接是否closed来决定服务端是否调用end方法，推送数据，这里跳过end方法是否会对服务端的连接产生影响？

closed意味着早已经end， 这个是没问题的。