launch_tests: support ShadowSocks

In fact, nothing more has to be done: autoconnect should be enabled and
compared to SSHTunnel, we no longer have one connection as tunnel.
launch_tests: tcpdump on lo: filter proxy port

we don't need info to redsocks, reduce r/w
launch_tests: remove pcap distant if error
launch_tests: remove local pcap if error

if not able to restart proxy
launch_tests: check config at the beginning