virsh: iptables command should wait for lock
virsh: iptables command should wait for lock

iptables command needs to acquire exclusive locks
when accessing xtables, to behave correctly in potential
case when there could be another one already running,
we should use --wait option to give it time for doing the operation.

In this case even small number like 1seec is way more then enough
since we are just processing piped input, first command needs like
0.007sec on node with commonly populated tables.

Should fix issue which appears as:

  TASK [remove iptables rules created by infrared, by comment] *******************
  task path: .../infrared/plugins/virsh/cleanup.yml:37
  fatal: [hypervisor-1]: FAILED! => {
      "changed": true,
      "cmd": "set -euo pipefail\n for table in \"-t nat\" \"\"\n do\n iptables ${table} -S | awk '/Infrared/ {$1=\"-D\"; print $0}' | xargs -r -L1 iptables ${table}\n done",
      "delta": "0:00:00.004517",
      "end": "2020-02-10 11:02:20.164544",
      "rc": 4,
      "start": "2020-02-10 11:02:20.160027"
  }
  STDERR:
  Another app is currently holding the xtables lock. Perhaps you want to use the -w option?

Change-Id: I546b333c7cfaf66f2cb63128a729942a2a41cd07

redhat-openstack/infrared,redhat-openstack/infrared,redhat-openstack/infrared