1. Fix a bug that when the BBR pacing speed is very low, it takes too long to close an idle UDP session.
2. Show packet number in mieru get connections and mita get connections command for easy debugging.

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1. 修复了当 BBR 配速非常慢时，关闭空闲 UDP 会话所需的时间过长的问题。
2. 在 mieru get connections 和 mita get connections 命令中显示数据包编号以方便调试。