sw test tool: Change a process that sends a packet one time to a method

In a case of sending packets continuously, methods of STATE_FLOW_MATCH_CHK and STATE_UNMATCH_PACKET_SEND should not send any packets.
Chainging a process to a method avoids this issue.
sw test tool: Rename STATE_UNMATCH_PKT_SEND to STATE_UNMATCH_PKT_RECV

And rename _test_unmatch_packet_send() to _test_unmatch_packet_recv().
This method is now not sending any packets.
sw test tool: Enable sending packets continuously