quic: suppress expected net.ErrClosed errors on UDP conn close

[requilence]

• Skip logging net.ErrClosed errors when closing UDP connections in QUIC transport
• This error is expected when both the timeout goroutine and normal close goroutine race to close the same connection
• Also fixed typo "upd" → "udp" in log message

[github-actions]

New Coverage	55.9% of statements
Patch Coverage	50.0% of changed statements (1/2)

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