Close DCP connections during bufferAck transmit errors

In MB-55019, it has been observed that when socket timeout happens, KV will close one side of the TCP connections and projector will not close its side of the connection. This will lead to Write errors to socket as the socket is closed. Ideally, projector should exit mutation processing in this case but projector will continue to listen on the TCP connections. This will lead to indefinite wait.

The fix for this issue is to exit mutation processing when buffer-ack transmit errors are seen in projector