test: imfamy: Allow broken images

If ping succeed but fail to check if netconf port is open,
the testsystem will hang forever.

This will allow totally broken images to be loaded at the device.

test/infamy/netutil.py

@@ -1,11 +1,8 @@
 import socket
 
-def tcp_port_is_open(host, port):
+def tcp_port_is_open(host, port, timeout=3):
     try:
-        ai = socket.getaddrinfo(host, port, 0, 0, socket.SOL_TCP)
-        sock = socket.socket(ai[0][0], ai[0][1], 0)
-        sock.connect(ai[0][4])
-        sock.close()
-        return True
-    except Exception:
+        with socket.create_connection((host, port), timeout=timeout):
+            return True
+    except (socket.timeout, OSError):
         return False