fix: connection leak when poller close connection but onRequest callback just finished

[joway]

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fix

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fix: 当对端关闭连接但是 OnRequest 回调刚刚返回时，连接可能泄漏的问题

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en:
Triggered Case:

1. client write and wait read
2. netpoll server OnRequest: read and write , OnRequest returned but still hold processing lock
3. client read finish and close connection
4. netpoll server receive EPOLLHUP and detach FD and call closeCallback but try to get processing lock failed
5. netpoll server OnRequest: release processing lock and return OnRequest
6. nothing will check connection state again so connection may leak.

Occur mainly in UDS server with short connection client . For TCP case, close a connection may not so quick to pass to server thread so server have a chance to finish OnRequest callback first.

zh(optional):

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