hs-test: experimental support for multiple test instances

- appending PID to interface and container names
- added a check for used IP addresses
- TestEnvoyProxyHttpTcp and TestTcpWithLoss are broken when running multiple instances

Type: test

Change-Id: Ib917079ec7cf851dee59ff9c67e74f48c7c5e3c6
Signed-off-by: adrianvillin <avillin@cisco.com>
diff --git a/extras/hs-test/linux_iperf_test.go b/extras/hs-test/linux_iperf_test.go
index 47ebd03..06247e4 100644
--- a/extras/hs-test/linux_iperf_test.go
+++ b/extras/hs-test/linux_iperf_test.go
@@ -14,7 +14,7 @@
 	s.assertNil(err, err)
 	s.log("server running")
 
-	ipAddress := s.netInterfaces[tapInterfaceName].ip4AddressString()
+	ipAddress := s.getInterfaceByName(tapInterfaceName).ip4AddressString()
 	go s.startClientApp(ipAddress, nil, clnCh, clnRes)
 	s.log("client running")
 	s.log(<-clnRes)