Add "-d 1" option to the ncat client.

In nc run as client, when it is provided by the nmap (nmap-ncat package
in Centos/RHEL for example) it could happend that client which was
started with input string given through pipe (echo "test" | nc ... ) was
closed sooner than it received response from the nc server. In such case
nc client was finished without error (exit code 0) but also without
printing any message from server and that causes tests failures.

To avoid that there is option "-d 1" (--delay) added. According to the
nc man page [1] this option can be used to configure "Wait between
read/writes".

[1] https://man7.org/linux/man-pages/man1/ncat.1.html

Change-Id: Id49654aa5ca59eeb0585646d3fd5aa0de22337b5

neutron_tempest_plugin/scenario/base.py

@@ -76,9 +76,11 @@ def get_ncat_server_cmd(port, protocol, msg=None):
 
 def get_ncat_client_cmd(ip_address, port, protocol, ssh_client=None):
     cmd = 'echo "knock knock" | nc '
+    ncat_version = get_ncat_version(ssh_client=ssh_client)
+    if ncat_version > packaging_version.Version('7.60'):
+        cmd += '-d 1 '
     if protocol.lower() == neutron_lib_constants.PROTO_NAME_UDP:
         cmd += '-u '
-        ncat_version = get_ncat_version(ssh_client=ssh_client)
         if ncat_version > packaging_version.Version('7.60'):
             cmd += '-z '
     cmd += '-w 1 %(host)s %(port)s' % {'host': ip_address, 'port': port}